Enemies

Enemies, also known as monsters, are the many antagonistic creatures and entities the player will encounter throughout the game.

Fiend Folio's most prominent feature is its massive variety of new foes, adding 500+ monsters to The Binding of Isaac: Repentance as of The Reheated Update.

This page is about enemies and monsters added in Fiend Folio. More information about monsters in general can be found in the vanilla page.

Enemy List
Chapter 1						Chapter 2						Chapter 3
Basement		Cellar		Burning Basement		Caves		Catacombs		Flooded Caves		Depths		Necropolis		Dank Depths
Chapter 1.5						Chapter 2.5						Chapter 3.5
Downpour			Dross			Mines			Ashpit			Mausoleum			Gehenna
Chapter 4						Chapter 4.5			Chapter 5						Chapter 6
Womb		Utero		Scarred Womb		Corpse			Cathedral			Sheol			Dark Room
Other
Ascent & Home									Miscellaneous

Enemy List

Chapter 1

Basement

Name	Icon	Description
Slammer		Leaps off-screen, then slams down, attempting to fall on Isaac.
Wimpy		Leaps off-screen, then slams down, moving towards Isaac. Moves with shorter but more frequent jumps than Slammer.
Red Horf		Remains stationary, puffing up when Isaac gets too close. Explodes into a ring of 8 projectiles when puffed up for too long. Explodes into 4 projectiles if killed when not swollen.
Mutant Horf		Remains stationary, immediately creating two projectiles that orbit around it after spawning. Whenever one of the projectiles is destroyed, a new one is quickly created.
Mr. Horf		Chases Isaac. When it gets close enough, it will stop to launch its own head at him. The head then becomes a Horf, and the body becomes a Pacer or Gusher.
Mr. Red Horf		Chases Isaac quickly, moving faster than Mr. Horf. When it gets close enough, it will stop to launch its own head at him. The head then becomes a fully swollen Red Horf, and the body becomes a Pacer or Gusher.
Morsel		Quickly chases Isaac. Usually found in groups of 2-4.
Pester		Chases Isaac. Spawns with an Eternal Fly. Has a chance to turn into a Pacer or Gusher on death. The Eternal Fly will continue orbiting the Pacer or Gusher spawned.
Slim		Slowly follows Isaac. When it draws close, it will attempt to smack him with its arm. If it hits a wall or an obstacle, it will stop to spray a few blood projectiles. When it dies, it has a chance to leave a Limb behind.
Limb		Remains stationary, hopping towards Isaac if he gets too close.
Bowler		Slowly walks towards Isaac. Eventually will throw its head at him, becoming a Loafer. The head will roll for a short while, curving towards Isaac.
Loafer		Moves towards the nearest Bowler Ball and picks it up, becoming a Bowler. If there are no Bowler Balls, or none it can reach, wanders around aimlessly like a Pacer.
Slobber		Wanders around the room, leaving a trail of slippery creep. Occasionally spits two consecutive projectiles towards Isaac.
Bleeder		Wanders around the room, leaving a trail of damaging creep. Occasionally spits two consecutive bloody projectiles towards Isaac.
Casualty		Slowly chases Isaac, leaving a trail of red creep. Once it takes enough damage, it will make a short leap towards Isaac, falling over and creating a larger pool of creep. When fallen over, it will stay that way and doesn't need to be killed in order to clear the room.
Dung		Slides aimlessy around the room. Occasionally will pause to release a barrage of projectiles towards Isaac. This attack stuns it for a short while, making it vulnerable to attacks.
Tall Boi		Remains mostly stationary, slowly sliding away from Isaac if he gets too close. Periodically whistles, summoning 3 Shitlings around to protect itself.
Shitling		Remains stationary, firing short-ranged projectiles at Isaac if he draws too close.
Shot Fly		Slowly flies towards Isaac. When damaged, performs a quick charge towards Isaac when lined up cardinally. Dies when it hits a wall while charging.
Shoter		Slowly flies towards Isaac. When damaged, splits into two charging Shot Flies in a V formation towards Isaac, when lined up cardinally. If killed before it attacks, will split and charge in two opposite directions horizontally to Isaac.
Square Fly		Slowly flies towards Isaac, while also moving in a square pattern. Blue variant moves clockwise, yellow variant moves counter-clockwise.
Bumbler		Slowly flies towards Isaac. When lined up cardinally, fires a linear burst of projectiles, propelling itself backwards until it hits a wall, stunning itself in the process.
Potluck		Flies towards a Urn to hide inside of it. Once in a Urn, after a while, it will spit out either a Spider or two coin projectiles towards Isaac. After attacking, will move to another available Urn in the room.
Poobottle		Floats above the room, immune to Isaac's attacks. Slams down onto poops, releasing 8 projectiles around it. Can be damaged during that time. If there are no poops in the room, leaves after a short while.
Butt Fly		Bounces around the room. When lined up diagonally, farts, propelling itself towards Isaac. Creates an additional fart on death.
Weaver		Chases Isaac while repeatedly burrowing in and out of the ground. If it lands on rocks, it will slide on top of them until it lands on the ground again.
Drink Worm		Burrows out of the ground in a random location and creates a floating projectile, then burrows back in. Burrows out elsewhere and sucks in the projectile towards itself, then repeats the process.
Benign		Bounces around the room, spitting a ring of three projectiles whenever it gets damaged.
Drumstick		Slides around through short and quick dashes. Occasionally fires four short-ranged projectiles in cardinal directions. On death, fires an arcing bone projectile towards Isaac. If it dies from fire, the bone will be burning and will leave a small, extinguishable flame.
Tap		Appears in pots, creating a ring of damaging creep around itself, then hides and reappears in a different pot. Is invulnerable, disappearing when the room is cleared.

Cellar

Name	Icon	Description
Spooter		Scuttles around, moving towards Isaac if close. Periodically fires single projectiles towards him.
Super Spooter		Scuttles around, moving towards Isaac if close. Periodically fires two projectiles in a V shape towards him.
Skuzz		Moves around by making high jumps, waiting for a while after each jump. Will hop towards Isaac if close.
Ring Skuzz		Moves around by making high jumps, waiting for a while after each jump. Attempts to arrange itself with others of its kind in a circle shape.
Army Skuzz		Moves around by making high jumps, waiting for a while after making 3 consecutive jumps. Will follow other Army Skuzzes, forming a line of them jumping one after another.
Baby Spider		Scuttles around, following Isaac if close. Does not deal contact damage, but will push Isaac slightly. Dies when stepped on.
Sticky Sack		Stays in one place, periodically spawning several Baby Spiders at once. Will regenerate its health slowly if not killed fast enough. Spawns a swarm of Baby Spiders on death.
Walking Sticky Sack		Roams around, periodically spawning several Baby Spiders at once. Spawns a swarm of Baby Spiders on death. Unlike the regular Sticky Sack, it does not regenerate.
Ransacked		Stays in one place, beginning to twitch more and more as time passes. Will eventually burst open, spawning one of the following: Dweller Bony Sackboy
Coby		Slowly chases Isaac. Upon death, spawns five Cobwebs in a plus shape, along with a single Baby Spider.
Nanny Long Legs		Remains stationary by default. If Isaac stands on any Cobwebs in the room, will rapidly chase him until he leaves the Cobwebs. If attacked while stationary, retaliates by spitting a singular projectile at him.
Brood		Buzzes around the room, following Isaac. After a while, it will throw the egg it is holding at him. The egg will burst into two Spiders, alongside creating a single Cobweb.
Zingling		Flies towards Isaac, periodically firing a projectile at him. When damaged, instead launches its stinger towards him, which bounces off of walls and rocks. After launching its stinger, falls and remains on the floor, twitching and leaving a small puddle of damaging creep underneath itself.
Beeter		Slowly flies towards Isaac. If close enough, begins to quickly fires bursts of three short-ranged projectiles around itself.
Hover		Buzzes towards Isaac, attempting to line up diagonally. When lined up, it will perform a short lunge towards him.
Honey Eye		Floats erratically around the room, occasionally lobbing large, arcing projectiles at Isaac that leave puddles of slowing creep.
Stingler		Bounces around the room, firing bouncing stingers whenever it takes damage.
Homer		Shortly after spawning, will launch its stinger at Isaac. The stinger is invulnerable and will constantly give chase, slowing down when turning. When its stinger is out, Homer will actively avoid Isaac. Homer slowly takes damage while its stinger is out. When Homer dies, its stinger is destroyed.
Honeydrip		Bounces around the room. Periodically slams into the ground with its stinger, creating a small rock shockwave ring, alongside spawning a single Dart Fly.
Marge		Slowly chases Isaac. Upon death, spawns several Swarm Flies.
Haunted		Slowly chases Isaac, occasionally firing single spectral projectiles towards him. Spawns a Yawner upon death.
Yawner		Relentlessly chases Isaac, flying across obstacles with slippery movement.
Crotchety		Chases Isaac, retaliating with singular projectiles towards him upon taking damage. On death, becomes a ghost that releases a wide spread of three spectral projectiles at Isaac before disappearing.
Dim		Relentlessly chases Isaac. On death, spawns a ghost that behaves similarly to Yawner, but cannot take damage. The ghost will disappear after a while.
Spoop		Floats around the room, seemingly avoiding Isaac. After a set amount of time, transforms into a Purgatory projectile, rapidly charging at Isaac and creating a ghostly explosion on landing.
Shirk		Remains stationary, periodically firing single spectral projectiles at Isaac. Upon taking damage, or when Isaac draws too close, teleports to another spot within the room. These spots are not random, and are determined by the room layout.

Burning Basement

Name	Icon	Description
S'More		Moves around by leaping off-screen and landing elsewhere. When it jumps, creates a line of gunpowder in its path, which is then ignited at the moment of landing.
Woodburner		Wanders around the room. Occasionally begins to spin its plank rapidly, causing it to bounce around while also creating short-lasting flames.
Wick		Slowly follows Isaac. Leaves small extinguishable flames behind as it takes damage. Occasionally spits out a larger flame towards Isaac.
Mr. Flare		Remains stationary, periodically spitting out flames around itself if Isaac draws nearby.
Mr. Crisply		Remains stationary, slowly taking damage over time. On death, releases a ring of extinguishable flames that persists on the floor for a while.
Powderkeg		Roams around the room, leaving a trail of gunpowder. If it touches a fire source, immediately explodes, igniting the gunpowder in the process.
Mullikaboom		Quickly chases Isaac. Upon death, creates a chain of explosions in a plus shape.
Fried		Crawls alongside one of the walls to line up with Isaac. Occasionally exhales a constant stream of flames.
Spitroast		Slowly flies towards Isaac. Upon death, releases a ring of flames.
Spark		Moves around the room by performing short dashes. Leaves a small extinguishable flame behind with each dash.
Charlie		Chases Isaac. Periodically lobs arcing chunks of coal at Isaac, which leave gunpowder on the ground on impact.
Sooty		Chases Isaac. Periodically lobs arcing chunks of burning coal at Isaac, creating a ring of flames on impact.
Big Smoke		Slowly moves towards Isaac. Occasionally farts, creating gunpowder around itself. Also creates gunpowder upon death.
Brisket		Sluggishly slides around the room. Periodically fires 4 slow-moving projectiles in either the cardinal directions. On death, creates a plus shape of gunpowder beneath itself. Brisket variants missing eyes and some of their teeth will send out projectiles in the ordinal directions and leave a cross shape of gunpowder.
Smogger		Actively avoids Isaac. Occasionally spits out a Dark Ball. If it touches a fire source, ignites and begins to relentlessly chase Isaac, while leaving a small trail of flames behind. If killed while ignited, leaves a large, extinguishable flame.
Fumegeist		Floats around the room aimlessly. Occasionally spits out a single Mote. If any Motes hit Isaac, causes the Motes to detonate, leaving gunpowder. Sometimes, will ignite itself along with all Motes in the room, then begins to pursue Isaac for a while.
Mote		Bounces around the room. If it touches a fire source, ignites and gains more speed, while periodically leaving small flames behind.
Smokin		Orbits closely around fireplaces. Fires a single projectile towards Isaac if the fireplace it is orbiting takes damage. If the fireplace is completely extinguished, begins to orbit Isaac at a distance instead, periodically speeding up to create a trail of flames. Does not need to be killed to clear the room, if not orbiting Isaac.
Flamin		Orbits around fireplaces, dealing contact damage. As its fireplace takes damage, its orbit will increase in radius and gains more speed. Dies when its fireplace is completely extinguished.
Trailblazer		Trails around the room, in a similar manner to Larry Jr. After taking damage, performs a short charge perpendicular to the direction it is currently moving, leaving a trail of flames behind.
Chili		Slides around, occasionally spitting out Litlings when Isaac is close.
Litling		Chases Isaac, performing quick dashes. Explodes after a while, leaving an extinguishable flame.
Commission		Flits around the room aimlessly, leaving a trail of gunpowder. If it touches a fire source, ignites and begins to move in a rapid and erratic pattern while leaving flames behind, before eventually exploding.

Chapter 1.5

Downpour

Name	Icon	Description
Buoy		Remains stationary until damaged or Isaac gets close. Afterwards randomly switches between firing short-ranged projectiles in random directions and erratically sliding around.
Buckethead		Chases Isaac, boasting a high amount of damage resistance. Becomes a Frowning Gaper when the bucket is destroyed. Can appear as a second wave in rooms with overturned buckets.
Mr. Sub Horf		Chases Isaac. When it gets close enough, it will stop to spin its own head at him. The head will release projectiles in all directions as it travels. The head then becomes a Sub Horf, and the body becomes a Pacer or Gusher.
Rift Walker		Occasionally swaps itself between being visible above the water, and being inside the water's reflection. When it's below the water, will chase Isaac quickly, with only its reflection visible. When it's above the water, will chase Isaac more slowly while occasionally spitting a tear at him.
Cushion		Actively avoids Isaac. Occasionally spits out a Strider. Spawns either 2 Striders or a Skipper on death.
Skipper		Makes quick, short leaps up to two to three times towards Isaac, or in a random direction.
Archer		Emerges from pits, spitting a Monstro's Lung burst of projectiles at Isaac before leaping towards him. Fires four projectiles in the cardinal directions upon landing, leaving its tail exposed for a moment before burrowing.
Mayfly		Slowly flies towards Isaac. On death, fires two projectiles in a V shape towards Isaac.
Mightfly		Bounces around the room. On death, pops into three V shaped projectiles in a triangle shape, along with a fountain of projectiles.
Dewdrop		Slowly floats towards Isaac. Periodically spits four projectiles that mimic Dewdrop's movements.
Floaty		Remains stationary, while taking heavy knockback from damage, causing it to spin and bounce around. Spews a line of green creep in the diagonal directions while spinning.
Mini-Min		Remains stationary, shooting a tear at Isaac when close enough. Occasionally submerges underwater and reappears in another location. On death, turns into a Level 2 Willo.
Bellow		Floats around the room, spawning tiny versions of Level 2 Willos to defend itself. Spawns only two at a time, and can have up to three orbiting it.
Tricko		Stays at a fixed distance from Isaac, firing projectiles at him occasionally. Relocates to another position after shooting or when taking damage. Does not need to be killed to clear the room, and will leave when such happens.
Ring Leader		Spawns with various Willos orbiting at a fixed position from it. Periodically commands its Willos to rotate around and all fire a projectile simultaneously. Will also respawn a Willo if its current Willo count is less than the number it spawned with. On death, all Willos that were orbiting the Ring Leader will resume its normal behavior.
Aleya		Floats around the room, avoiding Isaac if he gets too close. Spawns with special yellow Fireplaces dotted around the room. Uses the Fireplaces for various attacks: Makes a gesture, reigniting all extinguished Fireplaces and causing them to shoot a projectile at Isaac. Hides into one of the lit Fireplaces, periodically showing its face from one of them to fire a tear at Isaac. Extinguishing the Fireplace it is hiding in stuns it for a moment, making it vulnerable. Killing it extinguishes all yellow Fireplaces in the room.
Ignis		Teleports around the room, reappearing within line of sight of Isaac to attack. Fires a slow moving projectile that leaves smaller, trailing projectiles.
Bubby		Loosely floats towards Isaac. Periodically spins around, speeding up in the direction it was moving and firing 6 shots as it rotates.
Deathany		Has a variable amount of orbiting Willo wisps surrounding it. Killing all Willos orbiting it will cause Deathany to disappear. Appears at Isaac's starting position in a room shortly after he moves, and mimics his movements with a delay. A heavy mist is present in rooms containing it, indicating its presence.
Tango		Idles in place, before teleporting four times a very short distance towards Isaac, leaving three afterimages. After a short delay, these afterimages pop into four projectiles, alternating between the cardinal and ordinal directions.
Onlyfan		Dives into the water, creating three afterimages around the room. Will emerge elsewhere and then pose, causing all afterimages to shoot a wave of tears towards Onlyfan.
Zephyr		Floats after Isaac and has 2 attacks which it cycles between: Calls down a lightning strike directly on Isaac's current position. The bolt creates a ring of electricity that expands gradually for a moment. Raises itself into the air and charges towards Isaac while raining down projectiles beneath it
Cuffs		Chains two or more enemies together, limiting their movement and causing them to share their HP. Dies when the respective enemies chained to it are killed. Chain length and amount of enemies chained can vary. Does not deal contact damage, and Isaac, tears, and other entities can pass through it.
Glass Eye		Remains stationary, and is invulnerable to damage. Collects stray enemy projectiles in an orbit around itself and redirects them towards Isaac.

Dross

Name	Icon	Description
Shitty Horf		When Isaac draws nearby, begins to puff up. Explodes into a ring of 8 rotating projectiles when puffed up for too long, which circle out and back in. Explodes into 4 rotating projectiles if killed when not swollen.
Dollop		Follows Isaac, periodically launching a Drip at him. Only spawns a Drip if there are less than three Drips in the current room.
Connipshit		Stays stationary. Farts to scatter 4 gas clouds around the room, before lobbing an Ipecac projectile high in the air towards Isaac. Will only fart if there are less than 3 gas clouds currently in the room. Otherwise, it will only lob an Ipecac projectile. Only takes a small amount of damage from its own explosions.
Residuum		Bounces around the room. Constantly leaves a trail of gas behind it, which disappears upon bouncing off a wall.
Pipeneck		Walks towards Isaac. Attempts to hammer its head onto Isaac when lined up in the cardinal directions, splashing projectiles where it lands.
Shottie		Loads its barrel with 2 shots by dunking it underwater, filling it with detritus. After loading, will begin to chase Isaac and unloads its contents when in range. Can shoot either a spread of 4 projectiles, or a wad of toilet paper, which bursts into ring of 6 projectiles after a delay. When its barrel is emptied, it will flee from Isaac before reloading.
Coloscope		Walks towards Isaac. Launches a string of poop projectiles when in range, before sucking the line back in after a delay.
Stomy		Walks towards Isaac, lobbing a Butt Bomb towards him when in range. It will act as a standard lit bomb, despite its appearance. Are immune to explosions from its own bombs.
Wasty		Slowly chases Isaac, leaving a trail of slippery creep. If it walks into brown creep, made either by itself or by other enemies, its speed will greatly increase. On death, leaves a puddle of slippery creep.
Delinquent		Idles in place, urinating on the ground. When Isaac gets too close, or it takes damage, it begins to cry and crawl around the room, leaving a trail of damaging yellow creep. If left alone after enough time, it will become idle again and continue peeing.
Peepisser		Wanders around the room for a moment, before coughing up a bucket in which it will begin peeing in. After enough time has passed, or if interrupted, it will stop and kick the bucket towards Isaac, launching yellow projectiles. The bucket's behavior upgrades depending on how long the Peepisser has prepared the attack.
Cathy		Roams around the room moving in cardinal directions. Leaves a trail of yellow creep-leaving projectiles behind it.
Fishy		Steps around aimlessly, with an Eternal Fly orbiting it. When killed, the Necrotic underneath launches its Fish into the air towards Isaac, then gives chase. The Fish remains stationary and does not need to be killed to complete the room.
Fish		Remains stationary. Is orbited by an Eternal Fly.
Catfish		Emerges from pits, occasionally coughing up a Mayfly. After attacking, dives and reappears in another pit somewhere else.
Croca		Spawns in the room slowly moving from side to side against an adjacent wall or obstacle. When Isaac is in sight in front of it, it will charge forwards until hitting an obstacle. After each charge, alternates between freely chasing Isaac and staying attached to an obstacle.
Unshornz		Slides along around an obstacle or wall it's adjacent to, like Guts. Connects with other Unshornz to form a line. When an Unshornz in a line dies, other Unshornz behind it will branch off from their adjoining wall or obstacle.

Chapter 2

Caves

Name	Icon	Description
Milk Tooth		Flaps towards Isaac, occasionally making short, weak dashes towards him. Has very low knockback resistance.
Foamy		Drifts around the room, occasionally twitching. After a short while, enrages and makes a long diagonal charge, scattering projectiles when bouncing off walls.
Slick		Quickly chases Isaac, leaving a small trail of damaging creep. Has a chance to turn into a Stump on death. Usually found in groups of 2-4.
Stump		Wanders around randomly, leaving a small trail of damaging creep.
Pale Slim		Slowly follows Isaac. When it draws close, it will attempt to smack him with its arm. If it hits a wall or an obstacle, it will stop to spray a few blood shots and some creep around. When it dies, it has a chance to leave a Jim or Pale Limb behind.
Jim		Wanders around randomly, occasionally making slaps with its arm in random directions. If it hits a wall or an obstacle, it will stop to spray a few blood shots and some creep around. When it dies, it has a chance to leave a Pale Limb behind.
Pale Limb		Aimlessly hops around, sometimes moving towards Isaac if he gets too close and leaving small puddles of damaging creep.
Pale Bleeder		Wanders around the room, leaving a trail of damaging creep. Occasionally spits three consecutive bloody tears towards Isaac, with the third tear dealing a full heart of damage.
Balor		Chases Isaac, leaving a long trail of damaging creep. Occasionally shoots a large bloody tear at him that leaves a trail of damaging creep.
Eyesore		Chases Isaac. Shortly after spawning, its eye dislodges becoming a Gander which bounces around the room, and Eyesore will leave a trail of red creep. Occasionally fires a small cluster of bloody tears out of its empty eye socket when Isaac gets close. When Eyesore dies, its respective Gander dies.
Fathead		Slowly walks towards Isaac. On death, explodes into a large fart that deals no damage, and knocks back Isaac and other enemies.
Poople		Attempts to mimic Isaac's movement like a Dople, but with slippery physics. Leaves a trail of slippery brown creep. When bumping into an obstacle with enough speed, creates a burst of poop shots and spawns a Brownie Dip.
Dweller		Moves towards Isaac, shooting blood tears at him cardinally when in line of sight. Often spawns with a passive collectible from a set list and applies the effect onto itself.
Resident		Moves towards Isaac, shooting blood tears at him cardinally when in line of sight. Often spawns with an active collectible from a set list, and activates its effects based on the conditions of the room. Conditions depend on the active item held.
Fishaac		Flops aimlessly around the room, occasionally firing an inaccurate barrage of 4 tears at Isaac in cardinal directions. When damaged, will flinch and gain invincibility frames, similar to Isaac. Needs to be damaged 3 times in order to be killed, regardless of Isaac's damage stat.
Fossilized Boom Fly		Bounces around the room. On death, drops to the ground, creating a destructible boulder. The boulder explodes into a small fountain of rock projectiles when destroyed.
Edema		Spawns stationary, performing a charge in one of the diagonal directions until it hits a wall. After charging, stops for a while, before charging in a direction off by a 90 degree angle to the previous charging direction.
Weaver Sr.		Chases Isaac quickly while repeatedly burrowing in and out of ground, moving faster than regular Weavers. If it lands on rocks, it will slide on top of them, until it lands on ground again.
Bunker Worm		Burrows out of the ground in a random location, firing a large floating projectile towards Isaac before burrowing to another location. After burrowing out again, lobs a smaller projectile towards the larger one, causing it to explode into a ring of 8 shots.
Roly Poly		Slowly crawls around the room. Rolls towards Isaac when he gets in its line of sight, bouncing off of walls and obstacles.
Centipede		Crawls towards Isaac, moving over any rocks in the way. Can crawl into pits to come out of another pit in the room.
Snagger		Floats towards any pickups in the room, stealing any coins, keys, bombs, etc., and opens any chests or sacks. Stolen loot provide different effects depending on the pickup, either using them as projectiles against Isaac, or to give buffs to itself. If there are no pickups left in the room, simply floats towards Isaac, attempting to deal contact damage.
Hooligan		Quickly chases Isaac. Upon getting close enough, unleashes the contents of its sack head, dying in the process. Contents may include enemies to hinder Isaac, or helpful pickups. Does not spawn anything when killed by Isaac.
Globlet		Chases Isaac. When it dies, leaves behind a small goo pile before reviving after a short period. Can only revive once, and chases Isaac more erratically after reviving.
Meatwad		Slowly slides across the wall it is attached to. When lined up with Isaac, leaps towards the wall on the other side. If it touches a fire source, it will turn into a Grilled Meatwad.
Chunky		Slides aimlessly around the room. Occasionally hops, firing a large square shaped pattern of bullets that accelerates outwards. If it touches a fire source, it will turn into a Grilled Chunky.
Shiitake		Remains stationary, periodically firing a small projectile at Isaac when he gets close. Usually found in groups of 2-5.
Ramblin' Evil Mushroom		Patrols around the room in a predetermined path. Occasionally spawns a spore which floats down, spawning a Shiitake on landing.
Cordy		Periodically leaps off screen to land onto any Splattercaps in the room, triggering its attack. If there are no Splattercaps left in the room, makes aggressive hops towards Isaac instead.
Splattercap		Remains stationary, splashing a large amount of red tears when a Cordy lands on it. If they are the only enemies left in the room, explodes into a damaging fart.
Mobile Mushroom		Slowly walks towards Isaac with its cap down, taking reduced damage. Will occasionally stop to show its face, shooting 4 projectiles in either the cardinal or ordinal directions.
Wobbles		Floats around and makes short dashes towards Isaac. Occasionally, makes a faster dash and inflates its body, sending it floating farther.
Infected Mushroom		Has an aura around itself which inflicts confusion on nearby enemies. Afflicted enemies will periodically shoot slow, wavy projectiles at Isaac.
Cordify		Remains stationary, and periodically inflicts spores on a random enemy in the room. Enemies afflicted with spores explode into a poison fart upon death, which can destroy rocks. If there are no more available targets left, Cordify self-destructs in a large, explosive fart.
Smidgen		Remains stationary, and is immune to damage when its head is lowered. Is not immune to explosions, unlike regular Hosts. When Isaac gets close, lifts its head and fires two short-ranged projectiles in a V shape towards him. Has very low knockback resistance.
Red Smidgen		Remains stationary, and is always vulnerable. When Isaac gets close, lifts its head and fires spread of four short-ranged projectiles towards him. Has very low knockback resistance.
Hoster		Leaps off-screen, then slams down onto Isaac, before lifting its head to fire three blood shots in a spread towards him. Invulnerable to damage when not attacking.
Frowny		Remains stationary, occasionally spitting a single short-range projectile at Isaac. Has low knockback resistance, and can be pushed around without dealing contact damage. Is invulnerable, dies when the room is cleared.

Catacombs

Name	Icon	Description
Sniffle		Actively attempts to strafe around Isaac, while staying at a distance. Periodically fires fast, long-ranged bullets, attempting to lead them ahead of Isaac.
Tado Kid		Follows Isaac, occasionally firing a large homing projectile that splits into three smaller projectiles. The large projectile deals a full heart of damage. On death, has a chance to spawn a Tot.
Tot		Hops around the room, chasing Isaac when nearby. With each hop, it lobs an arcing homing projectile in the air.
Shrunken Head		Spawns in groups. The heads attempt to stick together, while chasing Isaac and occasionally spewing out blood shots at him.
Desirer		Hops around the room, splitting into 2 Waning Desirers on death. Waning Desirers hop faster and will split into 2 Diminished Desirers on death. Diminished Desirers hop even faster. Will hop towards Isaac when nearby.
Seducer		Hops around the room, sliding after every hop, leaving red creep and only stopping when reaching a wall or obstacle. Will hop towards Isaac when nearby.
Spitum		Remains stationary, spitting out clusters of green projectiles at Isaac that leave damaging creep.
Mr. Gurgle		Chases Isaac. When it gets close enough, it will stop to launch its own head at him. The head explodes on impact creating a pool of green creep, and the body becomes a Splasher.
Ragurge		Wanders around the room. Occasionally vomits out a large amount of projectiles in two types: red and purple. Purple projectiles home in on Isaac, while red linger in the air. After a while, Ragurge will suck all red projectiles back into its mouth.
Sackboy		Walks towards Isaac, occasionally spitting out two Spiders along with a swarm of Baby Spiders. On death, spawns more Spiders and Baby Spiders.
Spinneretch		Hops around the room, occasionally spawning a Spider Egg or spewing a stream of white projectiles towards Isaac.
Spider Egg		Remains stationary. When destroyed with tears, bursts into a swarm of Baby Spiders. When stepped on, creates a puddle of slowing creep in either a plus or cross shape.
Ogre Creep		Crawls alongside one of the walls to line up with Isaac. Periodically spits out a large, white projectile that deals full heart of damage. If the projectile hits Isaac, he will be slowed down for a short while. If the projectile hits the ground, it will create a Cobweb.
Scope Creep		Crawls alongside one of the walls to line up with Isaac. Periodically fires thin but long volleys of bullets, attempting to cut off Isaac's movement.
Warhead		Slowly bounces around the room. On death, creates a puddle of damaging creep and a ring of yellow projectiles.
Sourpatch		Slowly chases Isaac. On death, splits into its head and body.
Sourpatch Head		Hops around the room, chasing Isaac if nearby. Creates a small puddle of damaging creep with each hop.
Sourpatch Body		Wanders around the room, rapidly spewing out short-ranged yellow projectiles.
Bunch		Bounces around the room. On death, splits into three Grapes and three purple projectiles.
Grape		Bounces around the room quickly. On death, creates a small explosion.
Carrot		Rolls on the floor in vertical directions, dealing contact damage.
Mama Pooter		Remains stationary. If Isaac is below, Mama Pooter will spew out a large green projectile that leaves a trail of creep and pops into a volley of smaller projectiles. If Isaac is anywhere else, Mama Pooter will occasionally spawn Creepy Maggots. On death, explodes into a variety of flies and maggots.
Creepy Maggot		Roams around the room aimlessly, leaving a trail of damaging creep.
Flickerspirit		Slowly flies towards Isaac. Possesses a giant blue aura that renders all other enemies inside it invulnerable. Isaac's attacks will pass through enemies inside the aura, as if they had piercing.
Menace		Glides around the room. Eventually will charge into another enemy, possessing it in the process. If there are more enemies, a Menace will sometimes switch its possession target. Every time a possessed enemy is killed or when a Menace changes its possession target, it will scatter several spectral tears around. If there are no enemies to possess, Menace will simply charge at Isaac.
Dr. Shambles		Roams around the room. Fires homing, sparkling projectiles at damaged enemies, healing them upon landing. Throws bombs at Isaac.
Mothman		Wanders around the room. Occasionally screeches, causing an enemy closest to Isaac to release four projectiles in cardinal directions. Flies up in the air, becoming invulnerable to attacks, then dives down towards Isaac while raining down projectiles.
Drunk Worm		Burrows out of the ground and spits out three large projectiles that linger in the air, then burrows back in. Pops out elsewhere and sucks all three projectiles back in, then repeats the process.
Matte		Slowly roams around the room. Occasionally spits out a line of projectiles in a random direction that bounce off of walls and obstacles.
Colonel		Buzzes around the room. Spawns up to 8 Zingies that orbit around it. If it has less than 2 Zingies, spawns more until it has 8 again. Performs one of two commands: Causes all orbiting Zingies to fire a single projectile towards Isaac. Causes one of the Zingies to charge directly at Isaac. If a charging Zingy hits a wall, it stays there until the room is cleared. When Colonel dies, all orbiting Zingies will charge at Isaac.

Flooded Caves

Name	Icon	Description
Drop		Moves around the room by performing short dashes. Occasionally sinks into the floor, before attempting to land on Isaac from above. A blue mark will appear in the location Drop is about to fall in.
Dribble		Jumps in place, firing a spread of three tears at Isaac. Can perform a long dash, bouncing off of walls and obstacles. Splits into two Drops on death.
Nimbus		Walks around the room, occasionally stopping and creating a cloud that moves in one direction. The cloud constantly rains tears down, and disappears upon hitting a wall.
Floodface		Walks slowly, constantly spewing a fountain of tears in whichever direction it is facing. Comes in two variants: Eyeless Floodface roam around randomly. Floodface with eyes will chase Isaac.
Tubby		Walks towards Isaac. Occasionally will fart, creating a couple of randomly sized bubbles. If Isaac is close, may start stomping the ground, splattering tears around.
Geyser		Remains stationary, periodically coughing up 4 small bubbles and 4 medium water-filled bubbles in a ring around itself. The medium bubbles release four tears in the cardinal directions when popped.
Warty		Remains stationary, and periodically fires red bubbles towards Isaac that explode when popped. Is immune to explosions produced by bubbles.
Bubble Bat		Slowly flaps towards Isaac, occasionally spitting out a cluster of various bubbles at him. Upon death, falls to the ground, destroying any rocks below and creating a burst of tears around.
Cistern		Actively avoids Isaac. Occasionally spits out a bunch of bubbles. Sometimes, a Spider or an Attack Fly will be trapped inside one of the bubbles. Creates more bubbles upon death.
Bubble Blowing Double Baby		Slowly floats towards Isaac, occasionally spitting two small bubbles in a V-shaped trajectory. When killed, splits into two halves which each shoot single small bubbles at Isaac.
Globulon		Crawls around the room, occasionally spitting tiny bubbles at Isaac if he gets too close. If Isaac is far away, begins blowing up a large bubble filled with water before pushing it towards him. A fully-filled water bubble will pop into eight tears when destroyed. If interrupted while charging up the bubble, it will make a small hop in surprise and toss the bubble at its current state.
Gutbuster		Crawls quickly towards Isaac, immune to any form of damage. Occasionally will spit an Offal that will emerge from a random place in the room While the Offal is released, Gutbuster stays in one place, occasionally spitting out three bone projectiles in a quick succession towards Isaac. If the Offal happens to move under Gutbuster, it will suck it up and start chasing Isaac again.
Offal		Spawned by Gutbuster, but can be also found on its own. Slowly slides towards the Gutbuster it is linked to. If it has no linked Gutbusters, slides randomly around the room.
Eroded Host		Remains stationary, immune to damage when its head is lowered and skull is intact. When Isaac gets close, lifts its head and spews a fountain of yellow projectiles at him. If it takes damage while it is spewing projectiles, it will stop attacking and quickly lower its head. The skull can become damaged when its head is lowered, and eventually destroyed. The more damaged its skull is, the more projectiles it will spit out and the more frequently it will attack. If the skull is completely gone, it becomes vulnerable to damage even when closed.
Eroded Smidgen		Remains stationary, immune to damage when its head is lowered and skull is intact. The skull can be quickly destroyed when its head is lowered. When Isaac gets close, lifts its head and fires a small fountain of yellow projectiles in a V shape at him. When its skull is destroyed, fires the fountain in a spread of three.
Fishface		Follows Isaac, occasionally diving underwater and emerging somewhere else. Most often dives when too far away, and emerges closer to Isaac.
Frog		Emerges from pits and lobs a large blood projectile that splits into four smaller projectiles. After firing, dives and reappears in another pit somewhere else.
Madclaw		Walks towards Isaac, occasionally diving underwater and performing one of two attacks: Starts chasing with only its claw emerged, spreading tears in its wake. Follows Isaac while underwater and attempts to snap him with its claw. If there are Bubble Blowing Double Babies in the room, Madclaw will target them instead and will split them, creating a bunch of random sized bubbles. Madclaw cannot be damaged while completely underwater.
Zapbladder		Dashes around the room. Spawns with numerous Wires that orbit it. Periodically shocks all orbiting Wires with electricity, connecting each of them with a laser. If there are two or less Wires orbiting it, they connect to it instead of each other.
Wire		Usually spawns along with a Zapbladder and orbits around it. If there are no Zapbladders in the room, instead flits about randomly, or towards Isaac when close enough.
Anemone		Remains stationary, firing a random spread of one to four yellow tears towards Isaac that slowly accelerate.
Clam		Makes short hops around the room. Occasionally opens its shell revealing its pearl, before spitting a wavy barrage of projectiles at Isaac. Takes reduced damage while its shell is closed.
Puffer		Bounces around the room. Occasionally stops to inflate its entire body, before shrinking and spewing eight projectiles in a ring after a moment. If it dies while in this state, explodes into a large burst of projectiles.
Squid		Drifts around the room, making a few short dashes before firing a barrage of three inky tears at Isaac, and two additional ink tears in a wide V shape. The main barrage of tears bounce off the ground and leave black slowing creep where they land.
Sea Cucumber		Inches around the room in short bursts. Upon taking damage, charges up a massive barrage of brown tears, launching it forward.
Dolphin		Fires a projectile towards Isaac that bounces off walls and leaves a trail of tears, then dives into any nearby pits in the room. Hops out of a pit to a new location after a short period, and repeats the process.
Sponge		Orbits Isaac at a distance, growing bigger and becoming slower as it takes damage. After reaching its largest size, or after a period of not taking damage, shoots tears in six directions. Amount of tears created are based on the Sponge's size.
Panini		Hops around the room. Occasionally spits out a Drowned Charger. On death, spawns additional Drowned Chargers.
Isopoly		Slowly crawls around the room. Rolls towards Isaac when he gets in its line of sight, bouncing off of walls and obstacles. Functionally identical to Roly Poly.
Lightning Fly		Slowly flies towards Isaac. Periodically will start to produce electricity, making it move faster and become invulnerable for a short period.
Volt		Slowly flies towards Isaac. Periodically will start to produce electricity, making it move faster and become invulnerable for a short period. While electrified hitting it with tears will cause it to spark out short lines of electricity. On death sends out a ring of 5 projectiles which then shoot lasers outwards.
Drainfly		Floats above the room, immune to Isaac's attacks. Slams down onto poops, releasing 8 projectiles around it. Has additional effects that depend on the type of destroyed poop, such as spawning various Dips or Flies. Can be damaged during that time. If there are no poops in the room, leaves after a short while.
Aquabab		Remains stationary, spitting 2 projectiles at Isaac in a V shape twice when he gets close.
Wetstone		Constantly creates randomly sized bubbles around itself. Is invulnerable, deactivating when the room is cleared.
Bubble		Floats around. Pops when taking any amount of damage, or once the room is cleared. Can come in one of 4 different sizes.
Watery Bubble		Floats around. Pops when taking any amount of damage, or once the room is cleared. Can come in one of 3 different sizes. When destroyed, releases a number of projectiles in a ring based on its size.
Explosive Bubble		Floats around. Pops when taking any amount of damage, or once the room is cleared. Releases an explosion when destroyed.
Fly Bubble		Floats around. Pops when taking any amount of damage, or once the room is cleared. Releases an Attack Fly when destroyed.
Spider Bubble		Floats around. Pops when taking any amount of damage, or once the room is cleared. Releases a Spider when destroyed.
Isopoly Bubble		Floats around. Pops when taking any amount of damage, or once the room is cleared. Releases an Isopoly when destroyed.

Chapter 2.5

Mines

Name	Icon	Description
Glob		Slides quickly around the room, leaving a very short trail of hot lava creep. Occasionally sinks into the floor, before attempting to land on Isaac from above. Upon landing, leaves a larger puddle of lava creep and 3 extinguishable fires, before becoming extinguished itself. After becoming extinguished, attempts to roll towards a nearby lava pit to dive into and reignite itself.
Sizzle		Jumps in place, shooting a wave of fire at Isaac. Can perform a long dash, bouncing off of walls and obstacles and leaving a short trail of hot lava creep and extinguishable fire, then becomes extinguished. Upon becoming extinguished, hops towards a nearby lava pit to dive into and reignite itself. Splits into two Globs on death.
Fuego		Leaps out of lava pits at a predetermined trajectory, velocity and frequency. Bounces off of the ground, leaving small extinguishable fires with each bounce. Disappears when it lands into a pit.
Roasty		Emerges from lava pits, before making a leap towards another nearby pit, belly flopping on the ground halfway between it. Leaves a ring of fire waves around it when flopping on the ground. After reemerging, occasionally coughs a large magma ball towards Isaac that breaks into hot coals on hitting a surface.
Coalby		Chases Isaac, spawning extinguishable flames when it bumps into grids. Turns into a large coal when killed.
Coupile		Chases Isaac, spawning extinguishable flames when it bumps into grids. Upon taking enough damage, spawns a medium coal and turns into a Coalby.
Cairn		Chases Isaac, spawning extinguishable flames when it bumps into grids. Upon taking enough damage, spawns a small coal and turns into a Coupile.
Golden Fly Bomb		Quickly chases after Isaac. On death, turns into a small golden bomb that explodes shortly after. Upon exploding, it reforms back into its default form. Pink Gold variant drops bombs that can be picked up and thrown. Cannot be killed by default — it will reform infinitely until the room is cleared.
Anode		Roams around the room aimlessly. If there are more Anodes in the room, two (and sometimes more) of them will connect to each other with a Technology beam.
Grazer		Chases Isaac, periodically firing a small Tech-X laser ring towards him. There is a chance for the Grazer to misfire, causing itself to explode with a ring of 8 projectiles.
Technician		Floats aimlessly around the room, occasionally firing a long-ranged homing projectile at Isaac. If this projectile hits him, it does not deal damage, but instead creates 8 angled lasers in a ring from the point of impact.
Shock Collar		Bounces around the room. Creates a laser ring around itself that grows in size when Isaac gets too close.
Drillbit		Stays in one spot, launching a swirling ring of rock projectiles in a clockwise motion as it drills. Once it drills deep enough, leaps off-screen creating 4 rock projectiles in cardinal directions, before landing to a new spot.
Thumper		Remains stationary, periodically thumping the ground. Creates rock projectiles in cardinal directions when thumping, and causes all Nuberts in the room to simultaneously pop out of hiding.
Nubert		Roams around underground, indicated by shifting dirt. When a Thumper slams, pops out of hiding to fire a projectile at Isaac before burrowing back down. Always spawns along with Thumpers, and disappears when all Thumpers in the room are killed.
Quaker		Leaps off-screen, then slams down, attempting to fall on Isaac. Creates 4 rock projectiles in the cardinal directions along with a series of falling rocks where it lands. Cause Isaac to take knockback if he is standing in Quaker's zone of impact.
Stalagnaught		Spawns in the room burrowed under the ground, or hanging high above the room off-screen. When burrowed, attempts to repeatedly dig out directly under Isaac. When hanging, drops down when Isaac walks below it, indicated by its shadow. After dropping, digs down into the ground and begins behaving like the burrowed variant.
Speleo		Remains overall stationary but periodically attempts to leap on top of Isaac, marked the spot with a white reticle, creating a circular rock wave. If Isaac is moving, Speleo will try to predict his movement.
Anti Golem		Follows Isaac, producing and throwing Red Bombs at him. Anti Golem's own bombs can be picked up and thrown back by Isaac. Sometimes has a red bomb lodged in its head that drops as a standard Red Bomb pickup when killed. Can drop bombs to destroy any rocks in the way in order to pathfind to Isaac, even using them to create bridges over pits. Can only be damaged by explosions.
Crucible		Roams around the room, periodically spewing a constant fountain of rock projectiles, and spawning a Rock Spider. If it touches a fire source, becomes ignited, and its attack changes to create lingering hot coals and spawn a Coal Spider.
Blastcore		Floats towards Isaac, speeding up and leaving a wake of fire the more damage it takes. On death, explodes and releases a ring of fire waves, and a rock shockwave towards Isaac. The rock shockwave leaves behind pits where it travels.
Rufus		Remains stationary, getting angrier on taking damage, or when Isaac stays too close. Once provoked enough, detonates into a gigantic explosion, producing rings of falling rocks cascading outwards.
Grilled Chunky		Slides quickly around the room. Frequently hops, firing a large square shaped pattern of bullets at high speed. Spawned when a Chunky touches a source of fire.
Grilled Meatwad		Slowly slides across the wall it is attached to. When lined up with Isaac, leaps to wall on the other side, leaving behind extinguishable fires as it flies. Spawned when a Meatwad touches a source of fire.
Cappin		Roams around the room, invulnerable to damage. When Isaac crosses line of sight in any of the cardinal directions from it, will quickly charge in his direction. Flips over onto its head after hitting an obstacle or running a certain distance, leaving its underside exposed and able to be damaged. Flips back upright after a moment.
Spanky		Walks around the room, keeping a certain distance from Isaac. Occasionally picks up a pebble, and fires it at Isaac with its slingshot. Will pick up any tiny enemies in the room to use them as ammunition instead, including Smidgens and Frownies
Craig		Wanders around the room. If there is an active Bulb Rock in the room, Craig will jump on top of it and drain its energy. After a short while, he will fire a powerful yellow brimstone beam at Isaac.
Pillar John		Remains stationary and invulnerable and cycles between 2 attacks: Summons a number of stalagmites from the ground, creating obstacles. Creates a fissure from directly beneath Isaac's position.
Super Grimace		Remains stationary, and occasionally begins charging up a large projectile when Isaac is in sight and spits it towards him. This projectile splits into 4 projectiles in the cardinal directions on landing. Is invulnerable, deactivating when the room is cleared.

Ashpit

Name	Icon	Description
Flesh Sistren		Moves towards Isaac via a pattern of curves and stops. Every time it stops, fires two projectiles in a V shape towards him.
Shellmet		Roams around the room. Occasionally will begin to spin around, causing it to bounce around the room at high speed. When spinning, it receives increased knockback.
Spiroll		Constantly rolls back and forth in one axis. When lined up with Isaac, it will rapidly fire projectiles in his direction.
Prick		Consists of several segments stacked on top of each other. Depending on which segment is on the bottom, it behaves differently: Spike segment causes Prick to chase Isaac. When destroyed, it releases a ring of 8 spike projectiles. Turret segment causes Prick to slide randomly, while firing four spike projectiles, switching between cardinal and diagonal directions. Head segment always appears on the top of the stack, and causes Prick to aggressively hop around randomly, leaving an extinguishable flame behind.
Fireswirl		Slowly floats around the room. Occasionally begins to spin around, slowly dragging Isaac towards itself, while also periodically firing burning bone projectiles at him.
Pyroclasm		Teleports around the room. Each time it teleports, it fires four bone projectiles in a quick succession towards Isaac.
Dry Wheeze		Stays relatively distant from Isaac, periodically firing fast, long-ranged skull projectiles, attempting to lead ahead of Isaac. The skull projectile scatters into three bone or tooth projectiles on impact.
Marlin		Wanders around the room. When it lines up with Isaac, it will perform a charge towards him. If it hits a rock during the charge, it will launch that rock as a Rock Ball into the air above Isaac.
Fishfreak		Chases Isaac. On death, leaves an indestructible pile of bones that disappears only once the room is cleared. Occasionally will collapse into a bone pile to rise up from a bone pile closest to Isaac.
Clickety Clash		Slowly moves towards Isaac. On death, splits into two Clickety Clacks in their bone pile form, that quickly revive.
Ossularry		Crawls around the room with grid based movement similar to Larry Jr. When one of its segments is destroyed, launches three looping rib projectiles outwards. If the destroyed segment was a middle segment, Ossularry will split into two smaller versions of itself.
Skitter Skull		Crawls towards Isaac, occasionally snapping at him with its claws if close. If Isaac is too far away, it will fire a green projectile that bounces with a Flat Stone effect, leaving puddles of green creep. In some rooms, it will wait a while before emerging from the ashes.
Krass Blaster		Crawls quickly towards Isaac, immune to any form of damage. Occasionally will spawn two Dried Offals in the room and become immobile. While immobile, it will periodically fire a spread of three bone projectiles at Isaac. When it suck up its Dried Offals, it will resume its normal behavior.
Dried Offal		Slides around the room randomly, periodically firing four projectiles in diagonal directions. If there is an empty Krass Blaster, Dried Offal will attempt to reach it in order to be sucked back up.
Bombmuncher		Moves around by performing long leaps towards Isaac. Each time it jumps, it leaves a primed bomb behind.
Flinty		Periodically performs an off-screen leap, attempting to fall onto Isaac. When it jumps, it creates an explosion beneath itself, destroying the floor tile and creating a pit.
Blasted		Chases Isaac while burrowing underground. If close enough, it will burrow out and cough up a small bomb towards Isaac before jumping away while leaving a half-burrowed bomb that explodes when shot.
Ashtray		Remains stationary. After a set amount of time, it will consume the cigarettes in its mouth. Shortly afterwards, fires out a massive cone of flames towards the left or right, dying in the process.
Ztewie		Actively keeps its distance from Isaac. Occasionally will perform a short charge before jabbing its stinger out on a cord towards Isaac Usually appears in large groups.
Briar		Slowly flies towards Isaac. Periodically fires a stinger ball projectile that slows down to a stop before bursting into a ring of three bouncing stinger projectiles.
Beebee		Flies around the room diagonally. If crossing a cardinal, will perform a charge towards Isaac until it hits a wall and gets stunned for a moment. If Isaac is behind Beebee after the charge, it will fire out a boomeranging stinger at him.
Phoenix		Flies towards Isaac. When lined up cardinally, spits out a small bomb followed by a trail of bone projectiles, propelling itself backwards until it hits a wall, stunning itself in the process. Upon death, becomes a pile of ashes and remains stationary. After killing all other enemies in the room, begins to revive while spreading flames around, followed by four cardinal lines of flames. After resurrecting, its attacks become replaced: Spits orange projectiles that leave small, extinguishable flames instead of bones or bombs, and sends out two lines of flames in a V shape upon hitting a wall.
Gritty		Floats about the room, looking for rock balls. Will pick up Rock Balls and throw them at Isaac. If there are no Rock Balls in the room, it will leave shortly after.
Hangman		Floats around the room. Occasionally attempts to line up with Isaac cardinally and fires a line of three shots towards him. Rarely attempts to line up diagonally and fires an explosive shot.
Casted		Remains invincible and stationary, does not disappear after leaving the room. When shot at or when Isaac is in proximity, releases rings of fires around it for a period.

Chapter 3

Depths

Name	Icon	Description
Flanks		Chases Isaac. Occasionally, its head will begin to shake before teleporting, attempting to cut Isaac off. After teleporting, will become stunned for a moment before resuming its chase.
Flagpole		Consisting of 2 parts: a stationary body and a head that floats after Isaac. The head will fire a cluster of projectiles when in range of Isaac. Occasionally the body will reel in the head- bringing it into the cieling, before lowering it down again near Isaac. If the body is killed first the head drops down and bursts into projectiles and red creep. If the head is killed first the body gets up and becomes a Pacer.
Blare		Initially disguises itself as a Horf, and will shoot pathetic blood projectiles at Isaac. Once provoked, all Blares in the room will transform and begin chasing Isaac, periodically firing 2 blood projectiles in a V at him.
Striker		Slowly walks towards Isaac. Eventually will throw its head at him, becoming a Pale Loafer. The head will roll in a straight line, breaking any rocks on its path and releasing damaging rubble.
Pale Loafer		Moves towards the nearest Striker Ball and picks it up, becoming a Striker. If there are no Striker Balls, or none it can reach, behaves like a Pacer.
Smasher		Moves around by leaping off-screen and slamming back down, targeting Isaac. When it lands, it scatters a bunch of projectiles around and creates a puddle of damaging creep.
Stoney Slammer		Is invulnerable, dies upon clearing the room. Moves around by leaping off-screen and slamming back down, targeting Isaac. When it lands, it creates a small rock wave.
Hollow Knight		Roams around the room, invulnerable to damage. Has an orbiting brain that leaves a trail of damaging creep. When the brain dies, the Hollow Knight also dies.
Toxic Knight		Roams around the room only moving in the diagonal directions. Makes a slight charge when sighting Isaac, picking up a small amount of speed and stopping on hitting an obstacle. Only vulnerable from behind.
Squire		Chases Isaac. Swings its club, destroying any incoming projectiles. Occasionally swings its club quickly and violently while charging in a straight line.
Patzer		Protected by its invulnerable saw blade which blocks tears. Periodically moves to a spot somewhat close to Isaac, leaving its saw behind and becoming vulnerable. After a short delay, the saw follows its path returning to circling around it.
King		Slowly slides across the room, leaving a trail of creep. Protected by its invincible Pawns that are tethered to itself. Occasionally sends a Pawn out in a straight line. If low on Pawns, occasionally hops to fire 8 projectiles in a ring.
Scoop		Chases Isaac in a somewhat slippery way, leaving a trail of slippery creep. On death, releases a larger puddle of creep, scatters a few corn projectiles around and spawns a few Corn Dips.
Sundae		Chases Isaac in a somewhat slippery way, leaving a trail of slippery creep. On death, becomes a Scoop, while also releasing a larger puddle of creep, scattering a few corn projectiles around and spawning a few Corn Dips.
Soft Serve		Chases Isaac in a somewhat slippery way, leaving a trail of slippery creep. On death, becomes a Sundae, while also releasing a larger puddle of creep, scattering a few corn projectiles around and spawning a few Corn Dips.
Corn Load		Slowly slides around the room, leaving a trail of slippery creep and periodically firing arcing corn projectiles that create Corn Mines on impact.
Load		Slowly slides around the room, periodically firing arcing, explosive corn projectiles that scatter projectiles around and create pools of slippery creep.
Ghostse		Floats slowly towards Isaac. Occasionally, Ghostse will fire a constant volley of brown projectiles in a diagonal direction, propelling itself backwards. While performing this attack, Ghostse will disappear if it leaves the room boundaries, only to reappear elsewhere, usually somewhere near Isaac.
Gnawful		Shortly after spawning, becomes invisible. Its location is revealed only by its shadow and a small puddle of ectoplasm beneath it. If Isaac moves too close, Gnawful will reappear and perform three quick charges towards him, before disappearing and relocating somewhere else.
Peek-a-boo		Shortly after spawning, launches its eye out of it socket. The eye will bounce around the room, leaving puddles of damaging creep. When Isaac draws nearby, Peek-a-boo will periodically fire small volleys of spectral projectiles at him.
Temper		Stays passive and invulnerable until Isaac shoots at it or moves too close. When provoked, will become enraged and begins to relentlessly chase him. Occasionally will charge towards Isaac. Disappears when the room is cleared.
Banshee		Moves alongside walls and obstacles, akin to Guts, while remaining invincible. When left alone, it will gradually grow more upset until it begins constantly spewing out clusters of spectral projectiles. When attacked, it will return to being passive. Disappears when the room is cleared.
Spook		When Isaac enters a room with Spooks, laughter can be heard. Spooks will always spawn in groups, forming a line. Shortly after, Spooks will appear, mimicking Isaac's movement on a short delay. When another enemy is killed, they will speed up for a period. Spooks will disappear after clearing the room.
Mistmonger		Cannot be damaged, disappearing after clearing the room. Occasionally charges out the room and creates multiple harmless clones that charge across the entire room, obscuring vision.
Sleeper		Stays fairly stationary, invulnerable to damage. When shot at or when Isaac draws nearby, it transforms and obscures the entire room with dark static, leaving only small circles of vision around itself and Isaac. Will slowly move towards Isaac, attempting to deal contact damage. After dealing damage, disappears and removes the static shader. Disappears after clearing the room.
Wailer		Immune to any form of damage, moves alongside a predetermined path, periodically puffing up. While puffed up, it deals contact damage and blocks tears. Continues its behavior even after the room is cleared.
Dungeon Master		Spawns invulnerable to damage, along with orbiting Puzzle Key Ghosts. Will periodically launch the Key Ghost at Isaac. If a Key Ghost hits a Colored Key Lock, it will open it. If there are no Colored Key Locks to open or all orbiting Key Ghosts have been used, it becomes vulnerable and will begin to chase Isaac, occasionally swinging at him with its key.
G. Host		Remains stationary and invulnerable. Occasionally sends out its spirit, appearing as a ghost nearby Isaac. Its spirit will fires a spectral triple shot towards Isaac before slowly flying back to its skull. G. Host can only be damaged through this spirit.
Thousand Eyes		Floats around the room, periodically performing quick charges at Isaac. When killed, multiple pairs of eyes appear in pits of the room, some of them releasing more Thousand Eyes which immediately charge at Isaac and out of the room.
Scythe Rider		Floats around the room. Summons scythes that charge at Isaac, moving in long straight lines which redirect towards him after each charge.
Eternal Flickerspirit		Orbits an enemy, rendering it invulnerable to damage. If all vulnerable enemies are killed, its target becomes vulnerable.
Viscerspirit		Orbits an enemy, boosting its health.

Necropolis

Name	Icon	Description
Bone Worm		Burrows out of the ground in a random spot and fires four bones in the cardinal directions, followed by four additional bones in the ordinal directions, then burrows back in.
Sternum		Crawls around the room randomly. When it lines up with Isaac, it will charge towards him until it hits a wall. After hitting a wall, it will launch three rib projectiles outwards, then it becomes stunned for a short while. After recovering, it will retract the ribs back and resume its normal behavior.
Splodum		Crawls around the room randomly. When it lines up with Isaac, it will charge towards him until it hits a wall. After hitting a wall, it explodes, scattering three arcing bone projectiles around.
Doom Fly		Bounces around the room. Upon death, launches six boomeranging rib projectiles outwards.
Crepitus		Roams around the room, stopping to launch a volley of arcing bone projectiles towards Isaac if he is nearby.
Mr. Bones		Roams around the room aimlessly. If Isaac draws nearby, it will launch its own head, attempting to bite him, then retract it back. If its head is killed before the body, the body will become a Gusher.
Possessed		Roams around the room aimlessly, firing bones at Isaac if lined in a cardinal direction. Upon death, its skull falls to the ground and releases a Moaner.
Moaner		Chases Isaac for a while, before attempting to return to its respective Possessed's skull, reviving it. If there are no skulls to possess, it continually chases Isaac.
Cracker		Chases Isaac by performing off-screen leaps towards him. Each time it lands, it launches four rib boomeranging ribs that travel in a circular pattern.
Jawbone		Flaps towards Isaac, occasionally making short but quick dashes in his direction. Upon death, drops its skull, which can then be revived by Ribbones.
Ribbone		Slowly flaps towards Isaac. If there are any Jawbone skulls in the room, Ribbone will instead move towards them in order to quickly revive them.
Ribeye		Emerges from pits and fires three boomeranging rib projectiles towards Isaac. Ribeye is only vulnerable while attacking.
Unpawtunate		Remains stationary, occasionally firing explosive bone projectiles at Isaac, marked by a reticle. Upon death, its head dislodges and begins to chase Isaac while beeping, exploding after a short period.
Fracture		Chases Isaac, periodically firing arcing bone projectiles. As it takes damage, its head will crack more and more, increasing the amount of projectiles it can fire from 1 to 2 to 3.
Molar System		Slowly floats towards Isaac. As it takes damage, its teeth fall out and begin to orbit it. Each consecutive tooth will enter a larger orbit and will also move faster than the previous one. When Molar System dies, its tooth orbitals will remain lingering in the air.
Lil' Jon		Slowly bounces around the room, blocking projectiles and dealing contact damage. Dies when the room is cleared.
Spinny		Bounces around the room, while constantly shooting projectiles in a spiral pattern. Takes more knockback and fires faster when being knocked back.
Creepterum		Bounces around the room, periodically spawning swarms of Attack Flies and Spiders. When it dies, its body remains on the ground, dealing contact damage and turning invincible. Occasionally, the body will spawn several Attack Flies or Spiders, along with an Eternal Fly for itself, up to three. Once it spawns the 3rd fly, Creepterum will resurrect and resume its original behavior. Creepterum can only be killed as the last enemy in the room.
Baro		Floats around the room, occasionally launching a ball of flies towards Isaac. On impact, the ball splits into either three Swarm Flies or three Ring Flies. On death, Baro spawns a swarm of Swarm Flies.
Ring of Ring Flies		Flies towards Isaac. On death, splits into eight Ring Flies.
Calzone		Hops around the room, occasionally spitting out a random Maggot enemy. On death, spawns additional maggots.
Carrier		Crawls around the room. When Isaac is in line of sight, it will spit a spider ball at him, which splits into two Spiders on impact. On death, spawns Small Crazy Long Legs.
Gary		Bursts through one of the room's walls either randomly or after the room is cleared. Remains stationary, periodically spawning random maggots. Retreats upon being defeated and blocks the hole in the wall with rubble.
Dangler		Slowly floats towards Isaac, periodically firing an irregular spread of three bullets. When it damages Isaac, it will steal a couple of coins from him.
Tombit		Roams around the room, periodically slamming its body into the ground, spawning a Gravin. Invincible, dies after the room is cleared.
Gravin		Remains stationary, does not deal contact damage. Doesn't need to be killed in order to clear the room. On death, releases four short-ranged rock projectiles in cardinal directions.

Dank Depths

Name	Icon	Description
Blot		Moves around by performing short hops. Each time it jumps, it creates a small puddle of slowing creep.
Tar Bubble		When shot at, bursts into a volley of projectiles. When stepped on, creates a puddle of slowing creep, either in a plus or a cross shape.
Guflush		Actively follows Isaac, while slowly inflating the bubble on its head. As the bubble grows in size, Guflush's speed decreases. When the bubble is fully inflated, if Guflush takes damage or after a short while, it will pop the bubble, scattering large amount of projectiles that leave puddles of slowing creep. After popping the bubble, for a short while, Guflush will gain an increase in speed while also periodically firing arcing projectiles around.
Squidge		Slowly walks towards Isaac. Occasionally farts, launching three projectiles in the air. The projectiles create Tar Bubbles upon landing. On death, creates a pool of slowing creep.
Melty		Slowly chases Isaac. After taking enough damage, its head inflates, eventually leading into Melty bursting into a shower of projectiles and several Blots.
Pitcher		Chases Isaac. Periodically spits out a small volley of projectiles, along with several Blots.
Mr. Gob		Moves towards Isaac. When close enough, it will launch its head towards him. The head will drift for a while, while the neck continuously fires projectiles to the sides. On death, creates either a Gob or Black Globin's Body, depending on whether the body or the head was killed first.
Gob		Slowly moves towards Isaac. Occasionally fires a constant stream of arcing projectiles, while propelling itself in the opposite direction.
Gunk		Quickly chases after Isaac. Periodically fires a large projectile that leaves a trail of slowing creep and deals full heart of damage. When firing, Gunk will be pushed in the opposite direction. On death, falls on the ground as a large Tar Bubble.
Slag		Slowly slides along the walls. When Isaac lines up with it, it will leap to the other side, releasing a spread of 5 projectiles in an arc when it hits the opposite wall.
Gis		Wanders around the room. When Isaac is in line of sight, it will fire a constant stream of arcing projectiles, while also being slightly pushed back from the recoil. Couple of the fired projectiles will be larger and will create Tar Bubbles when landing on ground.
Slimer		Chases Isaac by making off-screen leaps. Each time it lands, it creates a pool of slowing creep and fires three arced projectiles that also create puddles of creep. If it lands in creep, it submerges while releasing a volley of projectiles along with several Tar Bubbles. It will then appear from another puddle in the room before resuming its behavior.
Gorger		Slowly crawls around the room, leaving a trail of slowing creep. If Isaac moves into line of sight, Gorger will perform a fast charge across the room, breaking any rocks on its path and dealing full heart of damage to Isaac. When it hits a wall, it will become stunned for a short while.
Sludge Host		Remains stationary, constantly creating slowing creep underneath itself. Periodically raises its skull to spit out a volley of projectiles that create slowing creep, along with two Blots in a v. Fires an extra splash of tar projectiles when slamming down. Can be damaged only when attacking.
Gobhopper		Moves around by performing long leaps and creating puddles of slowing creep wherever it lands. Occasionally will leap over to another puddle of creep to dive in and reappear elsewhere.
Skuzzball		Moves around by performing high jumps. As it takes damage, it throws out Spiders. When it dies, it transforms into a Small Skuzzball.
Small Skuzzball		Moves around by performing high jumps. As it takes damage, it throws out Spiders. When it dies, it transforms into a Skuzz.
Grater		Pops out of Grates and fires large, arcing projectiles at Isaac that deals a full heart of damage and creates pools of slowing creep. Sometimes all Graters in the room will hide and will perform a coordinated attack, causing all Grates in the room to rattle and spew tar projectiles up.
Clogmo		Appears in pipe openings, where it can be damaged. Will occasionally dive into the pipe system in the room and cause one of the pipes to bulge out. When the pipe with Clogmo inside is bulged out, all pipe openings in the room will constantly scatter projectiles around. Shooting at the bulged pipe will cause Clogmo to retreat and appear in a random opening again.
Piper		Roams around the room, periodically spitting out short lines of green, damaging creep. Every time it attacks, it switches between cardinal and diagonal directions.
Boiler		Remains stationary, occasionally releasing four large projectiles in cardinal directions, along with four smaller and slower projectiles in diagonals. The larger projectiles deal full heart of damage. If there are any Blots in the room, it will hop towards the Boiler and sacrifice itself to increase the Boiler's health and attack speed. Explodes on death and fires an inverted version of its standard attack.
Litter Bug		Crawls around the room, periodically firing arced projectiles at Isaac. The projectiles create fart clouds on impact that push Isaac back.
Toxic Litter Bug		Crawls around the room, periodically firing arced projectiles at Isaac. The projectiles create poisonous fart clouds on impact that deal damage to Isaac.
Trashbagger		Chases Isaac, occasionally spewing out random projectiles around. On death, spawns a variety of flies. Trashbaggers found exclusively in Dank Depths also leave a trail of slowing creep.
Dumptruck		Walks around the room, leaving puddles of black creep. If Isaac is nearby, it will create a Trashbag and fire a small volley of random projectiles towards him.
Dope's Head		Bounces around the room, blocking tears and is invulnerable to damage. Each time it bounces off a wall, its traveling speed briefly increases. Dies, when the room is cleared.
Bunkter		Emerges from its trashbag after a while or after all other enemies have been killed. Hops towards Isaac, occasionally spitting out a line of slowing creep, along with a large volley of various projectiles, in Isaac's direction.
Furnace		Remains stationary and is invulnerable. If there is black creep in the room, Furnace will begin to slowly boil it, causing small bubbles to appear. Stepping on the bubbles will harmlessly pop them. If the bubbles remain for too long, they will eventually burst into a shower of projectiles. Deactivates once the room is cleared.

Chapter 3.5

Mausoleum

Name	Icon	Description
Shaker		Moves around by leaping off-screen and landing elsewhere, prioritizing locations that cross over Isaac. While it jumps, it rains down slow falling projectiles along with a trail of cosmetic salt.
Rancor		When Isaac is lined up in a cardinal direction, charges in that direction until it hits an obstacle. If it has not sighted Isaac, it leaps offscreen to land near his location.
Clergy		Hovers around the room, with three projectiles orbiting it. When Isaac is in sight, launches one of its projectiles, which homes in at high speed.
Alfil		Roams around the room, charging at Isaac when lined up cardinally. Is granted a shield while other enemies are alive in the room, making itself invulnerable. Whenever Alfil blocks damage taken, causes a random enemy in the room to fire projectiles in the ordinal directions.
Zealot		Remains stationary, backing away from Isaac if he draws too close. After a moment, creates a white crosshair which attempts to target Isaac, gaining speed as it follows until it's beneath him. Eventually stops and after a delay calls down a large beam of light from the sky which lingers for a while.
Psychoknight		Roams around the room only moving in the cardinal directions. Makes a slight charge when sighting Isaac, picking up a small amount of speed and stopping upon hitting an obstacle. Only vulnerable from behind. When the eye on its back is open, following from behind causes Psychoknight's eyes to glow, and its head to shake. After staying behind for long enough, Psychoknight teleports to another cardinal direction close to Isaac, quickly charging towards him.
Pale Gaper		Chases Isaac quickly. Roars after a moment, greatly increasing its speed for a period. Continuously roars afterwards maintaining a high speed. Upon death, turns into a Pale Gusher. Can be Magnified into a Mag Gaper.
Pale Gusher		Wanders around and fires a stream of arcing projectiles in random directions. If close to Isaac then it will chase him and aim the projectiles towards him.
Pale Horf		Floats in place and fires projectiles towards Isaac at a quick rate. Has an infinite detection range. Can be Magnified into a Mag Horf.
Pale Clotty		Slides around the room randomly, periodically firing out 4 long-ranged waving projectiles in the cardinal directions. Can be Magnified into a Mag Clotty.
Sixth		Chases Isaac, lobbing a large homing projectile, which splits into a ring of 6 smaller homing projectiles while in the air.
Arcane Creep		Crawls alongside one of the walls to line up with Isaac. Shoots a large projectile directly forward that splits into two perpendicular shots when Isaac is to the side of it.
Psycho Fly		Bounces around the room slowly. On death, shoots a homing tear at Isaac, with all other Psycho Flies in the room doing the same.
Psystalk		Remains stationary. Spits a tear which slowly moves along either the vertical or horizontal axis, and attempting to follow Isaac at the opposite axis.
Stolas		Remains stationary. Occasionally spits a star projectile which moves around in an angular pattern, following Isaac and leaving a trail of smaller tears. Each projectile is connected to each other with a Technology Zero laser.
Morvid		Spawns perched on pillars, or on the ground, walking towards Isaac when grounded. After a moment, all Morvids in the room will simultaneously spread their wings and fly around the room above Isaac, and unable to be hit by attacks. One by one, Morvids in the room will spit a single feather projectile at Isaac. After enough time, Morvids will land back onto the ground, or perch back onto any pillars in the room. Morvids which perch on pillars will instead land on the ground if the rest of the enemies in a room have been killed.
Acolyte		Chases Isaac, utilizing teleporters in the room to reach him quicker. When one is killed, all others in the room will do a short lunge and gain a permanent speed boost.
Skulltist		Floats around the room. Occasionally activates the on-death effect of an enemy in the room that's closest to Isaac, without killing the enemy. If there is no valid enemy, spawns a Sucker to use instead.
Zissuru		Wanders around the room. Scatters a ring of flour around itself, before a purple smog begins filling the room outside the circle. If Isaac is not standing within the salt circle at the right time, he will take unavoidable damage.
Madhat		Floats around the room. Occasionally fires a colored projectile, leading it ahead of Isaac if he is moving. If the projectile hits Isaac, deals damage and applies a temporary debuff depending on its color: Purple projectiles applies Fear, preventing Isaac from firing tears. White causes Slowness, slowing down Isaac. Black applies a Curse of Darkness effect on the room.
Psyclopia		Chases Isaac, frequently spitting a projectile at him when in sight. After the projectile lands, Psyclopia will teleport to the point of that projectile's impact.
Alderman		Chases Isaac, sometimes spitting a homing projectile at him when in sight. After the projectile lands, Alderman will teleport to the point of that projectile's impact, producing a wave of fire in the 4 cardinal directions where it teleports.
Lunksack		Remains stationary, targeting enemies in the room one by one with a reticle, and placing a floating needle above them. After enough windup, stabs its voodoo doll bringing the needle above the enemy down, killing the enemy and shooting 8 needle projectiles from point of impact. If there's no enemies left to target, targets Isaac with its needle instead. The needle will narrowly miss Isaac if he is moving, but still shoots 8 needle projectiles from where it lands.
Shi		Floats towards Isaac, placing floating needle projectiles aimed at Isaac in cardinal directions, which launch forwards after a delay. If it gets close enough to Isaac, it will aggressively swipe at him with its claws.
Empath		Floats around in place. When an enemy in the room dies, makes a shocked expression before shrieking, firing 4 fast homing tears in the diagonal directions. Upon death, shrieks and causes all other enemies in the room to shoot 4 blood projectiles in the cardinal directions.
Grimoire		Floats around the room. Periodically opens up, revealing an eye which enchants an enemy in the room. Enchanted enemies leave behind cascading fire waves in the 4 cardinal directions on death. After enchanting an enemy, spits a homing fireball at Isaac, which explodes and creates cascading fire waves in the 4 cardinal directions upon landing. If there is no more enemies left to enchant, only uses the fireball attack.
Nihilist		Attempts to move towards enemy projectiles in the room, otherwise wanders aimlessly. Possesses an aura which causes all enemy tears passing through it to gain the Continuum effect, and greatly increases their range.
Looksee		Peeks from behind a random pillar in the room, spitting projectiles at Isaac which explode into a ring of 8 smaller shots on impact. Hides when Isaac attempts to attack it, or draws too close. Cannot be killed, and disappears when the room is cleared.
Temptress		Waits until all other enemies are killed or after some time passes, then emerges from a wall. Relentlessly chases Isaac, occasionally stopping to slam the ground and release two rings of blood shots that spiral outwards, while increasing in speed. On death, its head explodes, releasing a large volley of projectiles in the direction its facing.
Grievance		Spawns stationary, with a circular red zone centered around it. If Isaac enters this zone, the Grievance immediately dashes towards his direction, bouncing off walls and obstacles, before slowing to a stop. Cannot be killed, and deactivates when the room is cleared.

Gehenna

Name	Icon	Description
Bull		Appears in groups, but only up to 2 Bulls in the room will attack Isaac at a time. If lined up horizontally with Isaac, it may charge at him, leaving a trail of fire in its wake. Otherwise, it may spits a small cluster of extinguishable flames. Occasionally, all Bulls in the room will stop in place, and then shoot fire jets in the cardinal directions one-by-one.
Super Shottie		Paces around the room. Periodically spits a very fast moving hookshot towards Isaac that deals no damage, attempting to lead the hook ahead of him. If the hookshot lands, pulls the Super Shottie towards him, where it will blast a volley of blood projectiles at him once it reaches point blank range.
Discy		Walks around the room. On death, launches a Dangerous Disc towards Isaac, and turns into a Nobody.
Nobody		Paces around aimlessly. When attacked, or when Isaac draws close, gives chase and frequently spews a fountain of blood projectiles towards him.
Dangerous Disc		Invulnerable obstacle that moves along an obstacle or wall it's adjacent to, and deals contact damage. Can be spawned from Discies, or appear on its own.
Scowl Creep		Crawls alongside one of the walls to line up with Isaac. Shoots a slow-moving projectile which flies straight, following the Scowl Creep's movements like Tractor Beam.
Maze Runner		Walks randomly around the room, along with a Dople-like counterpart which mirrors its movements. Occasionally charges, spreading 4 projectiles behind it upon hitting a wall. When its counterpart dies, the remaining Maze Runner gains an increase in speed and begins chasing Isaac, charging more frequently.
Aper		Copies Isaac's movements and attack inputs, mirrored along an axis. Capable of gaining flight if Isaac has flight, or when moving over impassible obstacles. Up to three Apers can possibly appear at once, causing each to be mirrored on a different axis in the room. Projectiles shot by Aper have greatly reduced shot speed but linger for a long time.
Tagbag		Moves towards Isaac, slamming the ground when it gets close, creating a splash of blood projectiles. On death, rises into the air becoming intangible, and continues to move towards Isaac. Once above Isaac, or when all other enemies are killed, drops down, exploding into a larger splash of blood projectiles and a large red creep puddle.
Gabber		Roams around the room aimlessly. When Isaac fires tears, will stop moving to spew a constant stream of randomly angled projectiles towards him that stop in midair. When Isaac stops shooting tears, the barrage stops lingering and continues their trajectory. These projectiles freeze in place again if Isaac resumes attacking.
Gamper		Spawns chained to an immobile peg, periodically performing short lunges towards Isaac. The peg is the only part that can be damaged, while Gamper itself is invulnerable. Once damaged enough, a heart will burrow out of the ground from underneath the peg. The heart will then slide around and needs to be killed in order to defeat the Gamper.
Gutter		Appears near the edges of the room, then begins to lunge towards Isaac, attempting to slice at his current position before disappearing afterwards. Disappears permanently when the room is cleared.
Ripcord		Floats towards Isaac. Spews a string of interconnected Bead Flies in a diagonal direction, propelling itself backwards until it reaches a wall.
Bead Fly		Flies towards Isaac in diagonal motions. Connected to other bead flies as a chain.
Manic Fly		Flies around in place, barely moving. On death, spits a ring of 6 blood projectiles, with all other Manic Flies in the room doing the same.
Pitchfork Hitcher		Floats around the room. Periodically throws a flaming pitchfork towards Isaac, which produces a wake of perpendicular projectiles as it travels before embedding itself in a wall. The embedded pitchfork occasionally fires a volley of three projectiles at Isaac, and can be destroyed.
Kukodemon		Slowly flaps towards Isaac, spitting a large slow-moving projectile towards him, which creates a burst of projectiles 3 times as it travels. The first and second burst fires 4 projectiles in the cardinal and diagonal directions, with the final burst being a ring of 8 projectiles.
Haemo		Remains stationary, vomiting a volley of bloody projectiles and creep when attacked. While any Haemos in the room are alive, enemies that are killed will leave behind fleshy goo piles that slide away from Isaac. If these goo piles are not killed in time, the enemy that was originally killed will revive.
Lurch		Floats slowly towards Isaac. Occasionally opens its robe, spewing a volley of bloody projectiles that leave creep in a wide V shape, attempting to trap Isaac. Shortly after the volley finishes, follows up by launching a fleshy harpoon, attempting to skewer Isaac.
Punisher		Remains stationary, occasionally igniting and spewing a constant spiral pattern of fiery slow-moving projectiles.
Apega		Moves towards Isaac by making short hops. When in range, swings open its doors and fires a ring of 10 spike-shaped projectiles, which boomerang back in towards Apega. Can only be damaged while its attacking.
Eye of Shaggoth		Remains stationary, surrounded by a circular aura and moving a reticle vaguely towards Isaac's position. Enemy projectiles that enter the aura gain Eye of Occult-like properties, mimicking the movements of the reticle.
Sensory Grimace		Remains stationary, facing in a set cardinal direction. If Isaac makes a movement input in a certain direction, indicated by the arrows on it, it begins rapidly firing. Will continue firing as long as that input is held. Cannot be killed.
Thwammy		Spawns in the room rising up off screen, with its large shadow visible When Isaac crosses underneath it, quickly slams down, crushing both Isaac and any other enemies. Isaac will become comedically squished and have his movement slowed temporarily if he is caught underneath the slam.

Chapter 4

Womb

Name	Icon	Description
Spicy Dip		Slides around the room Periodically will curl up to start chasing Isaac with higher speed, taking wide turns.
Berry		Periodically will curl up to start chasing Isaac with higher speed, taking wide turns. On death, spawns 2-3 Spicy Dips.
Craterface		Floats around the room. Creates a pulsating ring of blood shots around itself and then releases them outwards.
Drooler		Slowly floats towards Isaac. Occasionally it will perform a sequence of three quick dashes towards Isaac, followed by creating a large pool of damaging creep underneath itself. If it damages Isaac during any of those three dashes, it will laugh, stopping the sequence.
Harletwin		Attaches itself to another enemy with a short cord. Occasionally screams, causing six blood shots to spread out of the attached enemy. If the attached enemy dies, the Harletwin dies instantly.
Nuchal		Floats towards Isaac, hanging from the ceiling with a cord. After taking enough damage, detaches itself from its cord and continues the chase on foot. The cord will continue floating after Isaac while dripping projectiles and red creep.
Punted		Floats towards Isaac, periodically firing wavy tears at him. After being defeated, its cord is cut and the Punted falls to the ground. While on the ground, it can be kicked around by shooting at it or pushing it. It does not deal contact damage in this state. When next to a pit, it will fall into it and disappear.
Forgotten Fetus		Spawns with Lil Al attached directly to it or with a cord. Slowly chases Isaac, occasionally firing a large projectile that leaves a trail of red creep. If the cord is broken or when Lil Al dies, Forgotten Fetus' projectiles will gain a burst effect in the form of a ring of projectiles and a small volley aimed at Isaac.
Lil Al		Spawns attached to Forgotten Fetus either directly or with a cord. If the cord breaks or Forgotten Fetus dies, Lil Al will start crying blood, splattering blood shots around and leaving puddles of red creep.
C Word		Remains stationary, periodically spawning Neonates. Dies upon clearing the room.
Neonate		Slowly floats towards Isaac. Occasionally fires a line of four gradually decreasing in size blood shots towards Isaac.
Thread		Chases Isaac by burrowing in and out of the ground. Only its tail can be damaged. When burrowing in, it leaves its tail stuck out for a while and spews two bursts of three blood shots.
Warble		Bounces around the room. Can be damaged only from behind. On death, creates a ring of bullets that linger in the air for a short while.
Strobila		Roams around the room. Can be damaged only from behind. When lined up with Isaac, will perform a charge towards him, until it hits a wall. While charging, it will periodically fire two projectiles in a V shape from behind.
Redema		Spawns stationary, performing a charge in one of the diagonal directions until it hits a wall, firing a single blood projectile at Isaac. After charging, stops for a while, before charging in a direction off by a 90 degree angle to the previous charging direction. On death, releases four blood shots in diagonal directions.
Globscraper		Slowly slides towards Isaac. When damaged, its lowest segment slides away, immediately reforming into a Globin or Gazing Globin.
Glorf		Remains stationary, periodically shooting a sequence of three projectiles towards Isaac. Upon death, collapses into a ball of flesh that slowly bounces around the room. If not killed fast enough, the ball will reform back into Glorf.
Globwad		Slowly chases Isaac. Occasionally farts, creating a pool of damaging creep, along with a ring of projectiles that linger in the air for a short while. On death, collapses into a pile of flesh that leaves a trail of damaging creep and actively avoids Isaac. If not killed fast enough, the pile will reform back into Globwad. If destroyed, the pile will split into two Globins in their goo form, along with shooting four projectiles in cardinal directions.
Toothache		Chases Isaac at a moderate speed. Eventually will trip and fall face down on the floor, scattering two tooth projectiles, creating a small puddle of creep and leaving a single tooth wedged into the ground. The tooth functions as an obstacle, deals contact damage and can be destroyed. After tripping for the first time, Toothache will increase its chasing speed and from now on, every time it falls over, it will scatter several blood shots instead of teeth.
Chops		Roams around the room aimlessly. Periodically fires a spinning rib projectile that bounces around the room and leaves a trail of blood shots behind. Up to four ribs can be fired consecutively, as Chops will need to reload before it can fire more.
Chummer		Relentlessly chases Isaac, charging at him when lined up cardinally. Upon death, collapses into a pile of flesh and bones, scattering two bone projectiles and spawning three Globins or Gazing Globins in their goo form. As long as there are other enemies alive, the pile will periodically scatter four bone projectiles around itself. When the room is cleared, the pile is destroyed.
Foe		Creates a ring of six blood shots that orbit it very closely. When damaged or when Isaac comes too close, extends the orbit of blood shots towards Isaac. After a while, retracts the orbit and regenerates any lost projectiles.
Quack		Hops around the room, spawning bombs inside gelatinous sacks. When destroyed, these sacks will shoot out four blood projectiles in cardinal directions and create a primed bomb. Occasionally, Quack will detonate all of the sacks, causing them to prime immediately, along with shooting out a ring of 8 blood projectiles on explosion.
Motor Neuron		Follows Isaac. Occasionally starts spinning its tentacle around. While the tentacle is spinning, any tears shot at Motor Neuron will be deflected.
Plexus		Remains stationary, periodically attacking by poking nerve endings out of the ground. The nerve endings have locations determined by the room creator and come in two variants: Fixed nerves that come out all at once. Delayed waves of nerves that continuously come out until the line hits a wall or obstacle.
Womb Pillar		Remains stationary and invincible. When Isaac draws nearby, begins to continuously spew out blood projectiles and creep around until he leaves the proximity. Continues its behavior even after the room is cleared.
Immural		Hangs down from the ceiling, invulnerable to damage. Connects any nearby enemies with cords, limiting their movement. When all connected enemies are killed, falls to the ground, scattering blood shots around.

Utero

Name	Icon	Description
Heartbeat		Slowly chases Isaac, continuously producing sounds of a beating heart. Occasionally will puff up and slightly decrease its chasing speed. When puffed up, whenever it takes damage, it will scatter a couple of blood shots around. When it dies, while puffed up, it explodes into a large amount of blood shots.
Valvo		Wanders around the room. Upon being shot at, it has a chance to eject a massive amount of blood shots towards Isaac in a volley fashion. Upon death, it leaves a single, large blood projectile that falls onto ground afterwards.
Jammed		Actively avoids Isaac, periodically spawning Smidgens. On death, spawns a Hostlet.
Red Jammed		Actively avoids Isaac, periodically spawning Red Smidgens. On death, spawns a Red Hostlet.
Tittle		Floats around the room diagonally, bouncing off walls, invulnerable to damage. Occasionally opens up and fires a spread of two short-ranged projectiles towards Isaac. This is the only time when it can be damaged. Very low resistance to knockback.
Bola		Remains stationary, launching its head, attached to its base with a cord, towards Isaac. The head drifts towards Isaac for a while, while a bloody clot in one of Bola's eyes starts growing. After the clot is fully grown, it explodes into a volley of blood shots. If Isaac moves too far away from Bola, it retracts its head back. While its head is retracted, it cannot take damage.
Astroskull		Bounces around the room, immune to damage. Has a specific amount of Lil' Junkies orbiting around it. The Lil' Junkies will slowly increase and decrease their orbit radius in a pulsating manner. Dies upon clearing the room, along with any Lil' Junkies orbiting it.
Sagging Sucker		Follows Isaac, firing a large volley of blood shots downwards when lined up diagonally with him. The volley will cause the Sagging Sucker to be repelled in the opposite direction, and launching itself towards Isaac if he is above it.
Trickle		Bounces around the room. After taking enough damage, it produces a fart that heavily knocks Isaac back and then transforms into a Skittering Trickle. In this form it skitters quickly after Isaac, occasionally releasing a ring of eight blood projectiles. If killed in either form, it releases a ring of twelve blood projectiles.
Magleech		Roams around the room aimlessly. If it bumps into a wall, it will stick to it and begin to puff up. Shortly after, it will launch itself away from the wall with high speed, while scattering a large amount of bone projectiles in the opposite direction.
Retch		Crawls around the room aimlessly. Occasionally stops to create a small shower of orange projectiles that leave puddles of slowing creep. On death, creates a larger puddle of creep.
Bladder		Remains stationary, periodically spitting out a line of yellow creep, along with several shots towards Isaac. Bladder will attempt to predict Isaac's movement, trying to cut him off with its attack.
Minimoon		Bounces around the room. Occasionally will stop its regular movement and start orbiting another enemy in the room. After a while, it will stop orbiting and resume its normal behavior.
Peepling		Floats around the room. Occasionally creates an arc of five tears around itself and then sends them away, aiming at Isaac.
Onlooker		Remains stationary, producing a harmless, semi-transparent laser in a specified direction. When Isaacpasses through that laser, the Onlooker will change it to an opaque, harmful laser for a short while. Continues its behavior even after the room is cleared.
Utero Pillar		Remains stationary and invincible. When Isaac draws nearby, spews out 1-3 Organelles. Continues its behavior even after the room is cleared.
Organelle		Moves around by performing short dashes in random directions. When touched, bursts into blood shots that leave puddles of damaging creep. Touching it will deal contact damage.
Cordend		Floats in one place, remaining invulnerable. Occasionally, it will extend its both halves to two sides of the room, connecting them with a cord. The cord can be shot at, forcing Cordend to close prematurely. Eventually will close by itself. Dies upon clearing the room.
Artery		Remains stationary and invulnerable in the ground. Will periodically spawn Mobile Blood Cells or Spinning Blood Cells depending on the room. These Blood Cells will travel to the nearest Vein and enter it. Stays active even once the room is cleared.
Vein		Behaves identically to Arteries but acts as the exit point for Blood Cells to enter.
Peepee		Hops around, occasionally spitting a large blood projectile towards Isaac.

Scarred Womb

Name	Icon	Description
Curdle		Slowly chases Isaac, while leaving a trail of damaging creep. On death, loses its armor, creates a small puddle of damaging creep and spawns 1-2 Leper Flesh. Curdles without armor chase after Isaac quicker and occasionally fire a single Haemolacria projectile towards him. Creates small puddle of damaging creep on death.
Nailhead		Slowly chases Isaac. If Isaac comes too close or Nailhead takes too much damage, its head explodes, scattering a few damaging nails that linger on the ground until the room is cleared. While at this state, Nailhead gains increased speed along with a trail of red creep.
Contestant		Spawns either with or without a screw. Contestants with the screw stay away from Isaac, while those without will loosely follow it. Periodically, Contestants with nail will launch it towards a Contenstant without a nail, effectively switching places with each other, while releasing a small volley of projectiles. Contestants who have ejected the screw will chase after Isaac.
Facade		Actively avoids Isaac. When shot at or when Isaac comes too close, changes its behavior and starts chasing him at high speed. Upon death, releases a ring of nine blood shots.
Vacuole		Wanders around the room. Periodically will mark four spots in the walls and suck in a blood projectile from each of those spots, creating a pattern in either a + or X shape.
Gleek		Slowly moves towards Isaac, leaving a trail of damaging creep. Switches between firing two large blood shots, that leave trails of damaging creep, in a V pattern and a spread of three small blood shots in a cone shape.
Incisor		Floats around the room. Occasionally will stab and take a bite out of the ground, before spitting a Leper Flesh at Isaac. If there is a Starving in the room, Incisor will launch Leper Flesh at it instead of Isaac, feeding it.
Starving		Shortly after being spawned, consumes its own head and spits a volley of blood and bone shots toward Isaac. Afterwards, seeks for other enemies to consume them and attack with the volley again. If there is an Incisor in the room, Starving will not target it and instead will use Leper Flesh that the Incisor spits. If there are no other enemies, Starving will occasionally bite the ground, followed by spitting a weaker-than-usual volley.
Mouthful		Walks towards Isaac. Occasionally farts, spawning 1-2 Morsels. Upon death, spawns more Morsels.
Lipoma		Slowly moves towards Isaac, occasionally burrowing into the ground and popping out somewhere else. When it takes enough damage, its head bursts and the Lipoma will begin to fire a constant stream of arcing projectiles that leave puddles of orange slowing creep, aiming at Isaac.
Pox		Slowly slides across the wall it is attached to. When lined up with Isaac, leaps to the wall on the other side, while leaving a trail of blood shots and damaging creep.
Cellulitis		Slowly slides around the room, leaving a trail of damaging creep. Occasionally hops in place, releasing a ring of 8 projectiles, along with a small volley aimed directly at Isaac. On death, splits into two Scarred Guts and a single Leper Flesh chunk. The Scarred Guts spawned from Cellulitis will also spawn a Leper Flesh chunk on death.
Dogmeat		Floats around the room. Occasionally spits three Nerve Clusters at Isaac. Upon death, spawns two Leper Flesh and one Nerve Cluster.
Flailer		Slowly moves towards Isaac. Occasionally will swing its head back and forth, attempting to slam it at Isaac. When it hits the ground, it releases four projectiles in diagonal directions. If Isaac is too far away it will spin its head around, releasing projectiles in all directions. If the head hits a wall while spinning, it will spawn a Leper Flesh. Depending on whether the body or the head was killed first, it becomes a Fistuloid or a Globin in its goo form respectively.
Brooter		Floats around the room. When lined up, launches a Chubber worm at Isaac, that flies off-screen. Occasionally spawns a random maggot. This can be either Maggot, Spitty or Charger.
Myiasis		Floats around the room. Occasionally spits out a Chubber worm in a diagonal direction. The worm will travel across the room, looping around the walls, Continuum style. Eventually the worm will return back to Myiasis, allowing it to launch again.
Head Honcho		Floats towards Isaac, occasionally spitting out a line of three blood shots at him. Alternatively, makes three charges across the room, similarly to War. During the charge, it will spit out a line of four blood shots. After taking enough damage, starts to bleed and begins accelerating towards Isaac. Upon getting close enough, explodes into a burst of blood shots and a single Charger.

Chapter 4.5

Corpse

Name	Icon	Description
Marzlammer		Chases Isaac by performing off-screen leaps. Whenever it lands, spawns 1-2 Small Maggots and fires three wavy lines of projectiles outwards.
Rotdrink		Slowly walks towards Isaac. As it takes damage, its skull gets more and more exposed and Rotdrink gains an increase in its chasing speed. Upon death, it spawns a Rotskull along with 1-2 Small Maggots.
Rotskull		Rapidly floats towards Isaac with loose movement. Highly resistant to knockback.
Rotspin		Can spawn with 1 to 4 heads. As it slides around the room, its heads rotate around, leaving poisonous gas. If the body is destroyed or when the heads are destroyed on their own, they explode into Small Maggots. If all heads are destroyed before the body, the body turns into a Spoilie in its goo form.
Spoilie		Actively chases Isaac. Upon death, collapses into a pile of flesh with spider legs. The pile will then act like a Level 2 Spider, until it eventually reforms back into Spoilie.
Sagging Spit		Follows Isaac, firing a volley of explosive Ipecac shots downwards when lined up diagonally with him, and creates a diagonal line of poison gas. The volley will cause the Sagging Spit to be repelled in the opposite direction, and launching itself towards Isaac if he is above it.
Droolie		Bounces around the room, periodically firing a spread of four projectiles that leave puddles of green creep at Isaac. Upon death, explodes into a ring of six projectiles that leave puddles of green creep.
Diagetic		Constantly chases Isaac by burrowing in and out of the ground. When burrowing out, it will create a trail of projectiles that follow it until it burrows back in. When burrowing back in, the trail of projectiles will follow its movement for a moment before then propelling itself towards Isaac.
Gut Knight		Roams around the room only moving in the cardinal directions. Makes a slight charge when sighting Isaac, picking up a small amount of speed and stopping upon hitting an obstacle. Possesses a line of projectiles trailing behind it, similarly to the item Akeldama.
Fingore		Actively chases Isaac, periodically reaching towards him with its hand, attempting to damage him.
Bamboo Cutter		Roams around the room. If Isaac lines up with it cardinally, it will attempt to snap at him with its bone claw. If a Frayed Nerve gets alerted, any Bamboo Cutters will rush towards that Nerve.
Frayed Nerve		Remains stationary and invulnerable. If Isaac approaches too close, it will alert all Bamboo Cutters in the room to rush toward it.
Torment		Remains stationary, occasionally performing one of the following actions: Releases a Cyst. Spews out a long-ranged volley of projectiles along with a line of red creep towards Isaac. Burrows into the ground, spawning two Rotten Gapers in random spots, then burrows back out.
Putrefatty		Crawls around the room. If Isaac is in front of it, fires a small volley of projectiles towards him, along with spawning a Small Maggot and a charging Charger. If Isaac is behind it, launches a Festering Guts.
Coconut		Remains stationary, occasionally sucking in Isaac for short while. Upon death, creates a massive fountain of Small Maggots and projectiles that create puddles of slowing creep.
Wheezer		Remains stationary, creating a cloud of poisonous gas around itself and slowly increasing its size, eventually being able to cover almost an entire regular room with gas. When it takes damage, the size of the cloud slightly decreases.
Whale		Slowly floats towards Isaac. After taking enough damage or after a while, its stomach explodes, releasing Whale Guts. The guts are connected to the Whale with a cord, not allowing both to move too far from each other. If the Whale is killed before its Guts, the Whale will fall on the ground and its head will explode, releasing a short burst of projectiles, along with a couple of Small Maggots and a Level 2 Charger. If the Guts are killed first, it will die without spawning any projectiles or maggots.
Whale Guts		Slides around the room, occasionally releasing three wavy lines of projectiles outwards.
Weeper		Randomly teleports around the room. Fires a sweeping laser with a visible telegraph beforehand, showing where it will cover.
Cancer Boy		Roams around the room, periodically spitting out 2 or 3 projectiles in a spread towards Isaac. When the projectiles hit something, they turn into Cancerlets.
Musk		Slowly moves towards Isaac. Occasionally will perform three subseqent dashes through the room, looping around the walls. When the 3rd dash ends, Musk will slam into the wall, scattering a couple of tooth projectiles around and spawning a Toma Chunk and 2 Cancerlets.
Foetus		Spawns attached to the ground with a short cord. After a while, it will release itself, revealing Foetu attached to the other end of the cord and shooting a ring of 8 projectiles around it. When released, it will relentlessly chase Isaac.
Foetu		When released from the ground, it will follow the attached Foetus, periodically spitting out spider ball projectiles at Isaac. On impact, the projectile will split into two Spiders. If the attached Foetus dies, Foetu will begin to relentlessly chase Isaac, and can receive heavy knockback.
Bub		Chases Isaac, and possesses a unique ability depending on what type of face it has.
Molly		Randomly switches between avoiding Isaac and chasing him. As it takes damages, its chunks fall off as Toma Chunks. When it takes enough damage, it begins to relentlessly chase Isaac, while leaving a trail of red creep. On death, spawns one more Toma Chunk.
Toma Chunk		Slowly floats towards Isaac. On death, spawns a Spider and scatters a couple of tooth projectiles at Isaac.
Small Conglobberate		Chases Isaac fairly quickly. Upon death, collapses into a pile of flesh that will reform back into Small Conglobberate if not killed fast enough. When it reforms, it fires a single arcing tooth shot in a random direction.
Medium Conglobberate		Chases Isaac with an average speed. Upon death, releases 4 shots in cardinal directions, spawns a Toma Chunk and collapses into two piles of flesh. The piles of flesh will attempt to combine into a larger pile that will reform back into Medium Conglobberate if not killed fast enough. When it reforms, it fires several blood and tooth projectiles in random directions.
Large Conglobberate		Chases Isaac with relatively slow speed. Upon death, releases a ring of 8 shots, spawns two Toma Chunks and collapses into three piles of flesh. The piles of flesh will attempt to combine into a larger pile that will reform back into Large Conglobberate if not killed fast enough. When it reforms, it fires a large amount of blood and tooth projectiles in random directions.
Molargan		Actively runs away from Isaac. Periodically fires an arcing tooth projectile that splits into four blood shots in cardinal directions and spawns an Oralid on impact. On death, explodes into a small shower of tooth projectiles, a ring of 6 tooth projectiles, and 1-2 Oralids.
Oralid		Spawns partially burrowed in the ground. When damaged, comes out of ground and begins loosely chasing Isaac.
Oralopede		Spawns partially burrowed in the ground, emerging shortly after, usually accompanied by a group of Oralids. Its Oralids will follow behind it as it marches towards Isaac. If it has less than 3 Oralids, it will make a short leap forward and embed itself into the ground, spawning 3 Oralids. Otherwise, it will eventually command its Oralids to chase Isaac with increased speed for a period.
Quitter		Crawls around the room erratically, while also avoiding Isaac. Occasionally will begin to suck in enemy shots and Isaac's tears until it consumes a certain amount or enough time passes. After consuming the tears, it will chew on them for a while, before spitting them back as a packed cluster of projectiles that split upon impact. The amount of projectiles in the cluster depend on the amount of shots consumed. It may also consume Small Maggots, Spiders, and Toma Chunks, and fire them at Isaac in the form of projectiles.
Tommy		Actively avoids Isaac, although very erratically. Occasionally spawns a flesh chunk, sending it to orbit an enemy close to Isaac in the room. The chunk takes reduced damage from attacks, and after enough time, it will transform into a Benny.
Benny		Actively chases Isaac. Occasionally stops to release a volley of blood and tooth shots.
Knot		Spawns in corners of the room. When Isaac gets too close or after the Knot takes damage, it will spawn several random spider enemies and then disappear.
Nematode		Remains stationary. Occasionally pops out of its body, firing three subsequent blood shots in a cone shape. While hidden, if it takes damage, it spits out three Toma Chunks in an arc, immediately destroying them, followed by firing four blood projectiles in diagonal directions. Upon death, spawns three Toma Chunks and releases a volley of shots towards Isaac.
Steralis		Ambushes Isaac after a certain period of time has passed in the room. Repeatedly burrows out of the ground, aiming to be underneath Isaac. When it burrows out, it scatters a bunch of tooth and blood projectiles around. After a while, it will burrow back, releasing a ring of 10 tooth projectiles.
Lurker		Fills in pits with its massive body that consists of various parts: Tissue - connects other parts. After the Lurker is killed, some Tissue chunks can become bridges, which can be walked on. Stoma - periodically spits out volleys of blood and tooth projectiles, along with spawning a Toma Chunk. Tooth - block Isaac's tears, can be destroyed with explosions. After the Lurker is killed, some Tooth chunks can become bridges, which can be walked on. Core (a.k.a. Eye) - the only part of the Lurker that can be damaged. When all Eyes have been killed, the corresponding Lurker will die. Stretch - connects Lurker parts that fill out separate pits.

Chapter 5

Cathedral

Name	Icon	Description
Chorister		Follows Isaac. Occasionally stops and creates a pattern of Crack the Sky beams around itself.
Enlightened		Chases Isaac, does not deal contact damage. Periodically fires four homing projectiles in cardinal directions, followed by additional homing projectiles in ordinal directions. Occasionally will stop and launch Inner Eye in the air. The Inner Eye will attempt to land on Isaac and will create a large pool of damaging creep after it touches the ground. While Inner Eye is out, Enlightened will be immobile and invulnerable to damage. Upon death, Enlightened will release Inner Eye permanently.
Inner Eye		Hops around randomly, leaving behind pools of damaging creep and firing homing projectiles towards Isaac. If there are any Unenlighted, it will move to posses them.
Effigy		Attaches itself to another enemy with a short cord. Occasionally screams, causing six homing shots to spread out of the attached enemy. If the attached enemy dies, the Effigy dies instantly.
Primemind		Floats around the room. Connects itself with another enemy using a purple Technology laser. While connected, slowly follows the connected enemy to keep the connection. The laser can connect to other enemies, creating a chain of lasers. If there are no other enemies, floats around harmlessly.
Deadfly		Floats around the room. Spawns with three Eternal Flies. Spawns Eternal Flies that move towards other enemies and then start orbiting them. If there are no other enemies, will spawn three Attack Flies. Occasionally will start bouncing around the room, spreading homing shots around for a while.
Holy Clotty		Spawns with an Eternal Fly. Slides around the room randomly, periodically firing out 4 homing projectiles in the cardinal directions. On death, creates a cross pattern of Crack the Sky beams.
Holy Wobbles		Floats around and makes short dashes towards Isaac. Occasionally, makes a faster dash and inflates its body, sending it floating farther. When doing so, leaves a cloud of sparkling yellow incense behind. The incense creates multiple small beams of light that can damage Isaac.
Cherub		Flies around the room by performing short, quick flaps in random directions. Occasionally will stop to fire a purple laser at Isaac, sweeping the laser towards him in a cone. Immediately after the attack ends, fires a single homing projectile with a Rubber Cement effect towards Isaac.
Warden		Floats around the room, avoiding Isaac. Periodically fires a long-ranged star-shaped projectile that homes in on Isaac. If Isaac gets hit with the projectile, a darkening effect will appear on screen with only a circle of light in the location Isaac was hit by the projectile. Isaac cannot leave the circle. The circle will disappear after a while, freeing him. Warden will not attack if Isaac has already been trapped.
Cherubskull		Spawns chained to a skeletal hand emerging from the ground. Floats around the room diagonally, blocking shots. When it reaches the maximum length of the chain, it will drag the hand for a short distance, and then it will begin to move in the opposite direction.
Armoured Looker		Floats around the room erratically. After taking enough damage, turns into a regular Looker.
Looker		Floats around the room erratically, creating floating purple shots. Sends these shots with high shot speed after Isaac after a short while.
Seeker		Slides across the room. Fires a precise line of seven homing tears towards Isaac, which angle around corners.
Watcher		Teleports in random locations in the room, leaving Watcher Eyes behind each time it teleports.
Watcher Eye		Remains immobile, periodically firing homing projectiles at Isaac.
Dogrock		Remains stationary. When Isaac is nearby, it will rapidly cause him to gain a large all stats down. The stats reset to their original value shortly after Isaac backs away. While nearby, the background of the room rapidly changes colors and a looping sound can be heard.
Congression		Moves across the room on a predetermined path. After it leaves the room, it reappears on the opposite side. Does not disappear after the room is cleared.
Specturn		Starts attached to a single enemy in the room, orbiting it. Causes other enemies in the room to also orbit the attached enemy. Disappears upon killing the attached enemy.

Sheol

Name	Icon	Description
Doomer		Chases Isaac by performing off-screen leaps, attempting to fall on top of him. Shortly after landing, it will stop and fire Brimstone beams in four cardinal directions.
Dread Maw		Actively chases Isaac. When damaged, spits out 4 projectiles in cardinal directions. On death, explodes into 4 projectiles in diagonal directions and an additional 4 big projectiles in cardinals. The big projectiles split into 2 streams of projectiles when they hit a wall or obstacle.
Dread Weaver		Constantly chases Isaac by burrowing in and out of the ground. While being underground, it creates rock shockwaves above itself, which can destroy rocks and damage Isaac. Upon death, creates an irregular ring of projectiles.
Thrall		Spawns chained to another enemy. Will periodically become invisible, along with making the chained enemy invisible as well. When the chained enemy dies, Thrall will teleport away.
Dominated		Relentlessly chases Isaac, occasionally performing a charge towards him, until it hits a wall. When spawned by Ms. Dominator and chained to her, it won't charge until it is released. When its chain is broken or upon death, releases six blood shots around.
Ms. Dominator		Spawns 1-2 Dominated and chains them to herself. Throws a Chain Ball at Isaac. Screams, releasing all chained Dominated and creating a ring of six blood shots around herself. After a while, Ms. Dominator may teleport to another location in the room, recalling all Dominated in the room back to herself.
Psi Hunter		Chases Isaac, occasionally making short dashes and swinging its blade. Can block Brimstone lasers by shielding its face with its arms and taking reduced damage from the beam. When a psionic enemy is closer to Psi Hunter than Isaac is, Psi Hunter will prioritize it and try to hunt it down. If there are multiple psionic enemies around, Psi Hunter may make a pause, before spinning its blade around, damaging anything in its path.
Psyeg		Remains stationary, can be destroyed by shooting at it or when Isaac or an enemy touches it. Deals contact damage to Isaac. When destroyed, spawns a Psiling.
Psiling		Moves around by performing short dashes. Periodically fires small homing projectiles towards Isaac.
Psleech		Roams around the room, charging at Isaac when lined up. While charging, it can teleport in front of Isaac if it misses him.
Psionic Knight		Roams around the room, only moving in the diagonal directions. When it lines up with Isaac, it will perform a charge towards him, firing a Brimstone laser from its back. Will accelerate forwards while charging until it hits a wall, stunning itself in the process. Only vulnerable from behind.
Outlier		Slowly slides across the wall or obstacle it is attached to. When lined up with Isaac, leaps to the wall or obstacle on the other side. While doing so, it can teleport in front of Isaac if misses him.
Crosseyes		Floats around the room. Creates two large homing projectiles around itself and then sends them after Isaac.
Foreseer		Floats around the room. Marks three spots around Isaac, trying to predict where he could move, then claps with its tentacles, creating explosions in those spots.
Observer		Appears in pits, slowly rotating, while projecting a semi-transparent, harmless laser in front of itself. When Isaac crosses the laser, Observer will stop rotating and fire an actual laser in the direction it is looking, creating a ring of 8 tears in the point of the laser's impact.
Umbra		Moves around the room by performing short but quick dashes. If there is another Umbra in the room, both attempt to approach to each other in order to fuse into a Blistered Umbra. If there are no other Umbras, it will dash towards Isaac in general.
Blistered Umbra		Slowly floats around the room. If Isaac gets close, splits into two separate Umbras again, launching them in the opposite directions.
Eclipse		Occasionally spawns Umbras. Has a set amount of Umbras it can spawn at once, which ranges from 1-5. Disappears upon clearing the room.
Sombra		Dives into the ground and follows Isaac as a moving pit, similar to those created by Little Horn. If Isaac falls into the pit, he takes damage and is thrown out after a while. Occasionally will fire a spread of three fast, large black projectiles towards Isaac.
Blazer		Bounces around the room, blocking shots and dealing contact damage. Occasionally will perform a quick dash towards Isaac if he is nearby, leaving a trail of blue flames behind.
Cauldron		Remains stationary and invincible. Periodically will create a continuum icon above a random enemy. After a short while, it will fire a beam towards that enemy, creating a clone of it. Becomes inactive after the room is cleared.

Chapter 6

Dark Room

Name	Icon	Description
Slim Shady		Slowly moves towards Isaac, periodically making quick dashes towards him, attempting to slap him. After making three dashes, jumps in place, creating a ring of explosions. The ring explodes a second time shortly after. Upon death, has a chance to leave a Red Hand behind.
Red Hand		Relentlessly chases Isaac, while constantly leaving a trail of lingering projectiles.

Other

Ascent & Home

Name	Icon	Description
Beacon		Buzzes around erratically, making quick dashes. Occasionally winds back and charges towards Isaac, only stopping and stunning itself if it hits a wall. If it comes into contact with Isaac, it will stick to him and drain 3 active item charges. It can drain charges into the negative.
Dizzy		Bounces around the room, while constantly shooting projectiles with a Rubber Cement effect in a spiral pattern.
Reaper		Floats around the room, periodically spawning spinning scythes in one of the two following patterns: Spawns four scythes around itself, that spiral outwards. Spawns four scythes in the corners of the room, that move directly at Isaac.
Roy Geralt Dericott II		Walks after Isaac, creating a large electric ring around himself. After awhile, absorbs the ring before firing a massive electric Brimstone laser towards Isaac. Rotates the laser to follow Isaac. Explodes on death.
Missing Link		Moves towards Isaac, shooting blood tears at him cardinally when in line of sight. When damaged, will flinch and gain invincibility frames, similar to Isaac. Needs to be damaged 5 times in order to be killed, regardless of Isaac's damage stat. Often spawns with a high-quality passive collectible from a set list and applies its effect onto itself.
Mag Gaper		Relentlessly chases Isaac, breaking any obstacles it runs through.
Mag Horf		Remains stationary and constantly fires large projectiles towards Isaac. These projectiles will burst into 4 smaller projectiles when landing. One of the 4 projectiles will be aimed at Isaac. Has an infinite detection range.
Mag Clotty		Slides around the room randomly, but will slide after Isaac if he is in range. Periodically fires 4 streams of 4 projectiles in the cardinal directions after each slide.
Accursed		Slowly moves towards Isaac. Occasionally will fire a spread of three spectral shots towards Isaac. When damaged, it will spawn a Murmur. On death, spawns three additional Murmurs.
Buckshot		Slowly floats towards Isaac. When lined up, it will begin to spit out charging Shot Flies at Isaac, while propelling itself backwards. Once it reaches a wall, it will loop back to the other side of the room, charging across the screen two more times until it finally smashes into the wall, releasing a ring of projectiles. While charging, it will adjust its path, slightly moving towards Isaac. On death, it will perform a final charge towards Isaac, smashing into a wall with high speed and scattering a large amount of blood shots everywhere.
Really Tall Boi		Remains stationary. When damaged, creates a line of poisonous gas towards Isaac, then summons two Dip and five Shitlings in an arc around itself. If there are any Shitlings alive, it will only create gas clouds.

Miscellaneous

Name	Icon	Description
Ticking Fly		Flies towards Isaac erratically. Explodes upon death.
Full Spider		Skitters around the room, jumping occasionally. Upon death, releases a ring of six blood shots around itself.
Custom Moter		Slowly flies towards Isaac. When killed, splits into singular Attack Flies and smaller, randomly shaped Custom Moters. The initial shape of the Custom Moter depends on the settings used by the room's creator.
Charmed Litter Bug		Crawls around the room, periodically firing arced projectiles at Isaac. The projectiles create charming fart clouds on impact that can charm enemies.
Fossil		Fires a small blood shot in Isaac's direction and disappears in order to reappear somewhere else.
Haunch		Remains stationary, attached to the floor or ceiling. When lined up with the Isaac horizontally, leaps to the other side.
Lonely Knight		Roams back and forth on the available ground. Can be damaged only from above.
Mold		Can be attached to walls, floor or the ceiling. When Isaac is in sight, lifts its skull to fire a quick line of four shots towards him. Invulnerable to damage when not attacking.
Sentry		Floats in one place, does not deal contact damage. When Isaac falls on top of it, he will be bounced upwards. Can be killed.
Sentry Shell		Floats in one place, does not deal contact damage. When Isaac falls on top of it, he will be bounced upwards. Cannot be damaged.
Elite Jon		Slowly bounces around the room, blocking projectiles and dealing contact damage. Persists between rooms and even floors.