Retribution Compatibility

Retribution
Developers	Ciirulean + Xalum
Release Date	28th of October, 2022

The Binding of Isaac: Retribution is a MOD that adds in a variety of new items, trinkets, enemies, and characters. Both it and Fiend Folio: Reheated feature extensive two-way compatibility, with items and mechanics introduced in both being compatible and edited to work with features in the other.

Item Compatibility

Perfectly Generic Object

Perfectly Generic Object
Flavor text	"Object Mimic"
Item Pool	Secret Room Secret Room

Main article: Perfectly Generic Object

• Perfectly Generic Object is a Fiend Folio active item that replicates the effects of Object-class pocket-items without consuming them.
• The following Retribution objects can have their effects duplicated by Perfectly Generic Object:

Name	Appearance	Mimic Charge	Description
Shattered Shard			Rerolls all items in the room into items of a higher quality.
Sword Capsule			On use, grants +0.5 Damage.
Heart Capsule			On use, grants a Red Heart container.
Clover Capsule			On use, grants +1 Luck.
Bow Capsule			On use, grants +2 Range.
Fling Capsule			On use, grants +0.1 Shot Speed.
Boot Capsule			On use, grants +0.1 Speed.
Tear Capsule			On use, grants +0.25 Tears.
Heart + Sword Combo Capsule			On use, grants a Red Heart container and +0.5 Damage.
Clover + Sword Combo Capsule			On use, grants +1 Luck and +0.5 Damage.
Bow + Sword Combo Capsule			On use, grants +2 Range and +0.5 Damage.
Heart + Bow Combo Capsule			On use, grants a Health container and +2 Range.
Heart + Fling Combo Capsule			On use, grants a Health container and +0.1 Shot Speed.
Heart + Boot Combo Capsule			On use, grants a Health container and +0.1 Speed.
Clover + Tear Combo Capsule			On use, grants +1 Luck and +0.25 Tears.
Bow + Fling Combo Capsule			On use, grants +2 Range and +0.1 Shot Speed.
Bow + Boot Combo Capsule			On use, grants +2 Range and +0.1 Speed.
Fling + Sword Combo Capsule			On use, grants +0.1 Shot Speed and +0.5 Damage.
Boot + Sword Combo Capsule			On use, grants +0.1 Speed and +0.5 Damage.
Tear + Sword Combo Capsule			On use, grants +0.25 Tears and +0.5 Damage.
Heart + Tear Combo Capsule			On use, grants a Health container and +0.25 Tears.
Clover + Bow Combo Capsule			On use, grants +1 Luck and +2 Range.
Clover + Fling Combo Capsule			On use, grants +1 Luck and +0.1 Shot Speed.
Bow + Tear Combo Capsule			On use, grants +2 Range and +0.25 Tears.
Fling + Boot Combo Capsule			On use, grants +0.1 Shot Speed and +0.1 Speed.
Fling + Tear Combo Capsule			On use, grants +0.1 Shot SPeed and +0.25 Tears.
Boot + Tear Combo Capsule			On use, grants +0.1 Speed and +0.25 Tears.
Clover + Boot Combo Capsule			On use, grants +1 Luck and +0.1 Speed.
Heart + Clover Combo Capsule			On use, grants a Health container and 1 Luck.

Penny Roll

Penny Roll
Flavor text	"Monthly allowance"
Item Pool	Boss

Main article: Penny Roll

• Penny Roll is a Fiend Folio passive item that spawns a Penny Trinket when obtained.
• The following Retribution trinkets can be spawned when picking up Penny Roll:

Name	Icon	Quote	Description
Grubby Penny		Wealth of friends	Spawns a blue spider when picking up a coin.
Rainbow Penny		Wealth of all	Mimics the effect of a random Penny Trinket when picking up a coin.
Yen Penny		Wealth of gacha	Chance to spawn a miniature stat-capsule when picking up a coin.

Broken Record + Broken Disc + Loaded D6

Broken Record
Flavor text	"Stuck on repeat"
Item Pool	None

Broken Disc
Flavor text	"1-minute free free free free free free"
Item Pool	None

Loaded D6
Flavor text	"Repeat your destiny"
Item Pool	Crane Game Treasure Room Ultra Secret Room Shop

Main article: Broken Record

Main article: Objects § Trial Discs

Main article: Loaded D6

• Broken Record is a Fiend Folio trinket that gives item pedestals a chance to grant items you already own.
• Broken Disc is a Fiend Folio object that grants 3-5 copies of a single item for 60 seconds.
• Loaded D6 is a Fiend Folio active item that rerolls item pedestals in the room into items you already own.
  • All of these items interact with a whitelist of items that have stackable effects.

The following Retribution items are whitelisted as stackable for the effects of these items:

• Arrow of Light.
• Axolotl.
• Azazel's Horn.
• Bad Apple.
• Baron Fly.
• Bedbug.
• Bob's Heart.
• Cactus.
• Cataract.
• Chastity Belt.
• Celestial Berry.
• Chimerism.
• Cholera.
• Chunk of Tofu.
• Coil.
• Cootie.
• Cracked Infamy.
• Defibrillator.
• False Promise.
• Forbidden Fruit.
• Frail Fly.
• Friendly Monster.
• Guppy's Pride.
• Heart Shaped Balloon.
• Hyperopia.
• Kapala.
• Laughing Gas.
• Mad Onion.
• Mark of Cain.
• Milk Teeth.
• Moxie's Head.
• Old Bell.
• Peashy.
• Philosopher's Stone.
• Photon.
• Reflux.
• Rickets.
• Silver Flesh.
• Slick Spade.
• Sloth's Toe.
• Smooth Stone.
• Soy Bean.
• Sunken Fly.
• Mom's Suppository.
• Tool.
• Toy Drum.
• Vanilla Wafer.
• Wax Wing.
• Weltling Sac.
• Booster Shot.
• Ham.
• Technology Omicron.
• Friend Folio.
• Bell Clapper.
• Brownie.
• Conjunctivitis.
• Milk of Baphomet.
• Myopia.
• Sour Patch.
• Bandage Binder.
• Sinner's Prayer.
• Red Chain.

Fuzzy Pickle

Fuzzy Pickle
Flavor text	"Reference up!"
Item Pool	None

Main article: Fuzzy Pickle

• Fuzzy Pickle is a Fiend Folio trinket that grants a damage up depending on how many items you currently own that are references to other pieces of media and pop-culture.

The following Retribution items are marked as references:

• Black Hammer - Game & Watch, Super Smash Bros.
• False Idol - Nicalis.
• Sculpting Clay - Four Souls.
• Pumpkin Mask - Community Remix.
• Bell of Circe - Paper Mario: The Thousand-Year Door.
• Bottled Fairy - The Legend of Zelda.
• Everlasting Pill - Charlie and the Chocolate Factory.
• Monster Candy - UNDERTALE, Pokemon.
• Moonlit Mirror - Moonlighter.
• Bone Saw - Team Fortress 2.
• The Iliad - Homer.
• The Odyssey - Homer.
• Coinflip - ULTRAKILL.
• Blazing Beak - Blazing Beaks.
• Lifeblood Syringe - Hollow Knight: Silksong.
• The Pig Bang - Humane Slaughtering Act.
• Bygone Arm - ULTRAKILL, The Legend of Bum-Bo.
• Celestial Berry - Celeste.
• Chunk of Tofu - Super Tofu Boy.
• Coil - Coil.
• False Promise - Nicalis.
• Friendly Monster - Aether.
• Heart Shaped Balloon - Downwell.
• Hundred Dollar Steak - Tyrone Rodriguez.
• Joyful - LISA the Joyful.
• Peashy - Cereus Peashy.
• Salesman's Eye - SCP Confinement Special - Anomalies!, SCP-1879.
• Shycoin - Cereus Peashy.
• Silver Flesh - OFF.
• Slick Spade - Homestuck.
• Tool - Petscop.
• Weltling Sac - Carious Weltling.
• Carapace - Hollow Knight.
• Spoils Pouch - The Legend of Zelda: Wind Waker.
• Friend Folio - Fiend Folio, Friend.
• Beeconomy - Hivemind.
• Milk of Baphomet - Baphomet, The Devil's Harvest MOD.
• Bootlicker - Mighty Jill Off.
• Red Chain - Pokemon Diamond, Pearl, & Platinum.
• Dominicus - The Locked Tomb.
• Polaris - Enter The Gungeon.
• Moxie's Eye - Four Souls.
• Rose Thorns - Hollow Knight, Minecraft.
• Strength Badge - Paper Mario: The Thousand-Year Door.
• Turnip - Animal Crossing: New Horizons.
• Thorn Ring - DELTARUNE.
• Crystal Shard - Nuclear Throne, Crystal.

The following Retribution items are marked as partial references, which grant a reduced damage increase:

• Cactus - Cereus Peashy.
• Kapala - Spelunky.
• Mad Onion - Minichibis.
• Rapture - The Simpsons Movie.
• Ham - Don't Starve Together.
• Sour Patch - Sour Patch Kids.
• Pride Pin - Alfred Kinsey.

Retribution also features Cursed Trinkets which have negative effects. Cursed trinkets have a special interaction with Fuzzy Pickle where they grant -0.25 damage each. The following Cursed Trinkets are marked as references:

• 12-Gauge Clay - This House Has People in It.
• Lame Sunglasses - Homestuck.
• Lament - Super Meat Boy.
• Impish Maize - Fiend Folio, Fiend.
• Grab Bag - Fiend Folio, Snagger.
• Viscalis - Fiend Folio, Viscerspirit.
• Heart of Ichor - Fiend Folio, China.
• Crow Mask - Blazing Beaks: Crow MOD.
• Joycon - Nintendo Switch.

Chastity Belt

Chastity Belt
Flavor text	"Your body is a temple"
Item Pool	None

• Chastity Belt is a Retribution passive item that grants a damage up negatively proportional to the number of keys held.
• Keys gain a unique skin while Chastity Belt is owned and disappear on room re-entry.
  • Spicy Keys have a unique skin for Chastity Belt compatibility.

Rainbow Penny

Rainbow Penny
Flavor text	"Wealth of all"
Item Pool	None

• Rainbow Penny is a Retribution trinket that mimics the effect of a random Penny Trinket when picking up a penny.
• The following Fiend Folio trinkets can have their effect mimicked by Rainbow Penny:

Name	Icon	Quote	Description
GMO Penny		Wealth of preservatives	Chance to take a random pill when picking up a coin. Scales with luck.
Molten Penny		Wealth of labor	Chance to smelt your current trinket when picking up a coin. Scales with luck.
Fuzzy Penny		Wealth of fuzz	Creates a blue skuzz when picking up a coin.
Sharp Penny		Wealth of pain	Small chance to activate "on damage" effects when picking up coins.
Egg Penny		Wealth of progeny	Chance to grant a Fragile Bobby when picking up coins.

Popsicle Stick

Popsicle Stick
Flavor text	"Say "ahhh!""
Item Pool	None

• Popsicle Stick is a Retribution trinket that spawns a random pill when a "negative" pill is consumed.
• The following Fiend Folio pill effects can trigger the effect of Popsicle Stick:

Name	Class	Effect
Haemorrhoids	Negative	Spawns a red poop.
Epidermolysis	Negative	Reduces the duration of your i-frames for the current room.
Lemon Juice	Negative	Reduces tear size.

Everlasting Pill

Everlasting Pill
Flavor text	"Stat-alteration free"
Item Pool	None

• Everlasting Pill is a Retribution active item that invokes a random non-stat-altering pill effect on use.
• The following Fiend Folio pill effects can be invoked by Everlasting Pill:

Name	Class	Effect
Melatonin	Positive	Makes enemies drowsy. Applies darkness for a few seconds.
Epidermolysis	Negative	Reduces the duration of your i-frames for the current room.
Clairvoyance	Positive	Removes the current floor's curses.

Slick Spade

Slick Spade
Flavor text	"Concupiscent hatred"
Item Pool	None

• Slick Spade is a Retribution passive item that grants a chance to fire tears themed after the 4 standard playing card suits.
  • Hearts tears inflict Charm.
  • Clubs tears inflict Bleed.
  • Diamond tears inflict Midas Freeze.
  • Spades tears inflict Fear.
• Using a playing card while this item is held will apply the effect of its suit to every enemy in the room.
  • This following Fiend Folio playing cards are whitelisted for this effect:

Charm

Three of Hearts

Jack of Hearts

Bleed

Three of Clubs

Jack of Clubs

Queen of Clubs

King of Clubs

Misprinted Jack of Clubs

Misprinted Two of Clubs

Midas Freeze

Three of Diamonds

Jack of Diamonds

Queen of Diamonds

King of Diamonds

Fear

Three of Spades

Jack of Spades

Queen of Spades

King of Spades

Bone Saw

Bone Saw
Flavor text	"Time to lose your medical licence"
Item Pool	None

• Bone Saw is a Retribution active item that can be used to instantly destroy "organic" beggars.
• The following Fiend Folio beggars can be killed using Bone Saw:

Poker Table

Zodiac Beggar

Evil Beggar

Fake Beggar

Cell Game

Hug Beggar

Cosplay Beggar

Sourpuss

Sweetpuss

Note

• Despite being organic beggars, Babi, Solomon, and the Blacksmith are excluded from Bone Saw for technical reasons.

Itempool Compatibility

Contraband

Main article: Contraband

• Contraband items are spawned when delivering Contraband or Small Contraband to a Dealer.
• The contraband item pool contains items that (with some exceptions) align with the following categories:
  • Syringes
  • Shrooms
  • Pills
  • Trafficked Organs
  • Foreign Implements
  • High Explosives
  • Banned Books
  • Cold Hard Cash
• The following Retribution items are added to the Contraband item pool:

Name	Icon	Quote	Description	Quality
Booster Shot		Compounding tears	-0.5 damage. Piercing tears. Each time a tear passes through an enemy, it gains x1.5 damage.	3
Lifeblood Syringe		Vital injection	Grants 2 soul hearts on use. Can only be recharged by killing Lifeseed Spirits that may spawn on enemy death.	3
Death Cap		Strength through mithridatism	Deals damage, grants a small all stats down, and adds +5% poison tear chance per use. On the 6th use, grants a large all stats up, and fully heals Isaac.	3
Devil's Tooth		Exsanguinating strength	Chance to fire a tear that Icarus-style upgrades enemies. Upgraded enemies have their health halved.	2
Mom's Suppository		Damage up?	Damage x1.5, then -2. Spawns 1-3 random pills on first pickup.	3
Everlasting Pill		Stat-alteration free	Mimicks the effect of a random, non-stat altering pill.	1
Melatonin		Zzz...	On use: Temporarily paralyses Isaac. Grants a tears up for the duration of the current room. Tears now apply a stacking slowness effect to enemies. After a few stacks, the enemy is Mom's Contacts-style frozen. While held, sleeping in a bed grants a heart container.	2
Bob's Heart		Volatile friend	Grants a trailing familiar that poisons enemies on contact. Grants a second trailing familiar that explodes on contact with enemies and respawns after a few seconds.	0
Dead Lung		Coughing up blood	+1 black heart. Spawn a large puddle of red creep when taking damage.	1
F.O.P.		Unbreakable	Upon hitting 0hp, all empty heart containers are converted into bone hearts.	3
Heart Rupture		Bursting hearts!	Enemies have a chance to launch a red heart pickup on death. The launched heart pickup can be caught to heal, but will splatter into a small creep puddle if left to hit the floor.	2
Hemorrhoid		Charged blood blast	When Isaac stops firing, a blast of blood projectiles is released opposite his movement direction. Taking damage spawns a red poop.	2
Tool		Remember being born?	Damage taken by enemies has a chance to be duplicated onto every other enemy in the room of the same type and variant.	3
Bone Saw		Time to lose your medical licence	Instantly kills shopkeepers and organic beggars. Low chance to spawn a body-part themed item when butchering a beggar. All butchered entities spawn 2 bone orbitals.	3
Eternal Bombs		Cast the beast into a lake of fire	+5 bombs. Bombs deal double damage to bosses.	3
Weltling Sac		Blood explosions	+5 bombs. A ring of blood explosions erupt around bombs when they detonate. Enemy projectiles in range of the blood explosions are destroyed.	2
Snap Bang		Snap, crackle, pop	On use plants a small explosive charge at Isaac's position. The landmine detonates on contact with enemies, dealing 10x player damage and confusing anything not killed.	2
Book of Mormon		Do you have a moment?	On use is held above Isaac's head. While held fears enemies in a large aura.	1
Friend Folio		Rival chapter	Temporarily grants a random Retribution familiar each room.	2
The Iliad		Achilles' wrath	"Throwable" item that launches a wall of spears from behind the chosen direction.	2
The Odyssey		Poseidon's wrath	On use: Chains enemies near Isaac with anchors. Breaks rocks in a similar radius. Spawns a large puddle of damaging blue creep at Isaac's position.	2
Coinflip		Ricoshot	On use throws a spinning penny onto the ground and removes 1 coin. Spinning pennies can no ricochet tears directly into enemies with a 1.5x damage multiplier.	3
Defibrillator		Starting to see black	Every other room, gain a 1.5x damage multiplier.	2
False Idol		An untrue faith	Grants +10.9 luck for the duration of the current room.	3
Laughing Gas		Winners don't use drugs	Tears and shotspeed up.	2
Philosopher's Stone		Health of wealth	+1 heart container. +3 golden hearts.	1
Milk of Baphomet		HP up, random on-hit effects	+1 heart container. When taking damage, activates a random on-damage effect.	2
Bootlicker		It hurts so good	+1 empty heart container. Until you beat the next available floor-boss: You can no longer pick up hearts. +0.25 damage permanently, for every time you take damage.	2
Monster Candy		Proof of evolution	Throwable item that permanently charms, and Icarus-style upgrades the enemy it collides with. If the thrown item misses, it is dropped on the ground as a pill. When the pill is used, it fully heals all friendly monsters.	2

Dire Chests

Main article: Chests § Dire Chest

• Dire Chest items have a rare chance to spawn when opening a Dire Chest.
• The dire chest item pools contain items that (with some exceptions) align with the following categories:
  • Immoral Heart Items
  • Items related to the characters of Maria's Imp Gang.
  • Risk/Reward Items
  • Flea Items
  • Fiend Folio Penny Trinkets

Collectibles

• The following Retribution items are added to the Dire Chest collectible pool:

Name	Icon	Quote	Description	Quality
Friend Folio		Rival Chapter	Temporarily grants a random Retribution familiar each room.	2
Milk of Baphomet		HP up, random on-hit effects	+1 Heart Container. When taking damage, activates a random on-damage effect.	2

Trinkets

• The following Retribution items are added to the Dire Chest trinket pool:

Name	Icon	Quote	Description
Spoiled Coin		Explosive economy	Enemies have a chance to drop explosive spinning coins on death. Spinning coins expire after 3 seconds.
Thorn Ring		Health-draining ice trance	3% chance to fire a thorn tear that instantly Uranus freezes enemies. While over 3 hearts, self-damage is taken every 30 seconds. Each time this damage procs it adds an additional 7% chance for 3 minutes.
Occam's Razor		Sacrificial glory	Using the Sacrifice Room or Sanguine Bond spikes grants an additional reward.

Glass Chest

Main article: Chests § Glass Chest

• Glass Chest items have a rare chance to be generated when a Glass Chest is spawned.
• The glass chest items pools primarily feature items that are made of glass or another fragile material.

Common Collectibles

• The following Retribution items are added to the Common Glass Chest collectible pool:

Name	Icon	Quote	Description	Quality
Stained Shard		Fragile protection	Summons a ring of fragile glass shards around Isaac. Shards can block enemy projectiles, and deal contact damage to enemies. Shards broken by a projectile will apply bleed to any enemy in contact with it.	1
Moonlit Mirror		Transdimensional bidding	Pickups in the room are transformed into 3-5 coins.	2

Rare Collectibles

• The following Retribution items are added to the Rare Glass Chest collectible pool:

Name	Icon	Quote	Description	Quality
Milk of Baphomet		HP up, random on-hit effects	+1 Heart Container. When taking damage, activates a random on-damage effect.	2
Bottled Fairy		Let your wounds heal	On use fully heals Isaac. Automatically used when taking fatal damage. If Isaac has no Heart Containers when revived, one is granted.	3

Trinkets

• The following Retribution items are added to the Glass Chest trinket pool:

Name	Icon	Quote	Description
Rainbow Penny		Wealth of all	Mimics the effect of a random Penny Trinket when picking up a coin.

Swine Beggar

• Swine Beggars are a Retribution beggar that can pay out with:
  • Blue flies/spiders.
  • A stat-boosting Capsule pocket-item.
  • A trinket from the Swine Beggar Trinket item pool.
  • A collectible from the Swine Beggar Collectible item pool.

Collectibles

• The following Fiend Folio items are added to the Swine Beggar Collectible pool:

Name	Icon	Weight	Description
GMO Corn		1	Isaac is immobilized and forced to consume 7 random pills. +1 Red Heart container. +1 damage.
Dice Bag		1	Spawns a sack familiar that follows Isaac and drops a random Glass Dice after every 8 rooms cleared. Glass Dice mimic their respective Dice collectible and break after use.
Lil Fiend		1	Spawns a familiar that flies diagonally across the room and has a chance to spawn an Evil Hollow Minion when colliding with an enemy or enemy projectile. Evil Hollow Minions disappear on room clear and will not drop a Black Heart.
Baby Crater		1	Spawns a familiar that follows Isaac around the room. Whilst Isaac is firing tears, Baby Crater creates a ring of tears around itself, similar to the enemy Craterface. Tears are released outwards when Isaac stops firing.
Randy The Snail		1	Snail familiar that retracts into its shell when hit by a projectile or walked into by Isaac, and will bounce around the room. Deals damage to enemies when bouncing into them.
Spare Ribs		1	+1 Bone Heart. Taking damage fires out rib projectiles that circle around Isaac. Rib projectiles return to sender and are destroyed only on contact with what fired them. Rib projectiles can destroy enemy projectiles.
Bag of Bobbies		1	Has a chance to spawn a Fragile Bobby familiar on room clear. Fragile Bobbies act similarly to Brother Bobby, but can die from taking enough damage from enemies.
Emoji Glasses		1	Isaac fires emoji tears that each have a unique effect. Cycles through 3 different emojis at a time.
Heart of China		1	+1 empty Red Heart container. Overhealing with Red Hearts charges a special health bar. Filling this health bar grants an empty Red Heart container. The number of hearts needed to fill this special bar scales with how many Red Heart containers Isaac has.
King Worm		1	On use, grants the effects of a random worm trinket for the current room. These effects can stack with multiple uses, including the effects of the same worm.
Cherry Bomb		1	On use, Isaac picks up a small red bomb that can be thrown. The bomb's explosion deals no damage to Isaac and can't break Rocks.
Snow Globe		1	On use, causes an earthquake that displaces all Rocks, Poops, and Metal Blocks in the room.
Wimpy Bro		1	Slammer familiar that jumps on enemies, dealing 5 damage.
Familiar Fly		1	Orbiting familiar that deals contact damage and blocks projectiles. Swells up when close to enemies, until exploding into a ring of 10 tears that can charm enemies. Respawns some time afterwards. Can charm Fly-related enemies in close proximity.
Model Rocket		1	+1.5 range. 2× shot speed multiplier. Tears accelerate from zero shot speed to normal shot speed on firing. Tears deal bonus damage based on their speed upon impact.
Rubber Bullets		1	Luck-based chance to fire bullet tears that bruise enemies. Bruised enemies take bonus damage from all sources of damage based on the number of stacks applied.
Leftover Takeout		1	+0.3 speed. 1.1× fire rate. 1.5× damage. +1.5 range. +1 luck. Luck-affected chance to fire a fortune cookie tear that deals 5% more damage and displays a fortune upon hitting an enemy.

Trinkets

• The following Fiend Folio items are added to the Swine Beggar Trinket pool:

Name	Icon	Weight	Description
Shard of China		1	Overhealing with Red Hearts fills a special health bar. Filling this health bar accumulates a damage boost, up to +1.5 damage with 3 hearts filled. Smelts itself once the bar is completely filled, making the trinket's damage boost permanent.
GMO Penny		1	Chance to take a random pill when picking up a coin. Scales with luck.
Bloody Sandpaper		1	Isaac no longer has movement momentum.
Fortune Grub		1	+1 luck. Beggars and Slot Machines will display a fortune when interacted with, or alongside their usual payouts.
Petrified Gel		1	Poops have a chance to be converted into Shampoo. Shampoo will no longer spawn Drops and will drop better rewards.
Solemn Vow		1	Allows the player to see enemy health.
Wackey		1	Key drops have an equal chance to become any key type.
Massive Amethyst		1	Shopkeepers in Secret Rooms are replaced with amethyst clusters. Amethyst clusters drop runes when destroyed.
Faulty Fuse		1	Increased chance for Copper Bombs to spawn.
Energy Searcher		1	Increased chance for Energy Cards to drop on clearing a room. Energy Cards have a 33% chance of spawning another one when used.
Fuzzy Pickle		1	Grants +0.1 damage for each reference item / trinket Isaac has, while active items grant +0.5 damage instead. Loose references only grant half of the corresponding damage.
Leftovers		1	Overhealed health gained from hearts will be left on the ground for later use.

Angel Swine Beggar

• Angel Swine Beggars are a type of beggar unique to Retribution's Mammon character.
  • Angel Swine Beggars appear in the Angel Room, replacing the item pedestals normally on offer.
• The following Fiend Folio items are added to the Angel Swine Beggar pool:

Name	Icon	Weight	Description
Dichromatic Butterfly		1	Isaac's hitbox size is reduced and indicated by a red marker over top of him. +0.2 damage for the current room when narrowly avoiding a projectile. Caps at +3 damage. Luck-affected chance to fire a tear with 1.25× damage and aggressive homing.
Crucifix		1	Enemies killed by tears will leave behind a short-lived ghost with an aura. Standing in the aura grants a boost to tear rate and damage, and makes Isaac's tears homing.
Page of Virtues		1	On pickup, spawns a random wisp. Whenever this wisp is destroyed, spawns a new random wisp.
Excelsior		1	Using active items will release fireworks, based on the item's amount of charge. Fireworks will home in towards enemies and explode.
Chaldean Axe		1	Periodically fire a piercing axe towards the closest enemy. The axe boomerangs back shortly after launch.
Black Moon		1	Isaac's tears gain a dark red glow. Killing an enemy with these tears creates a glowing red cross that damages enemies in an area of effect. Enemies killed by the cross don't spawn another cross.
Angelic Lyre		1	Rotates between 3 different "tunes" that passively change Isaac's tears into three different attack modes with their own stats and modifiers.

Demon Swine Beggar

• Demon Swine Beggars are a type of beggar unique to Retribution's Mammon character.
  • Demon Swine Beggars appear in the Devil Room, replacing the items normally on offer.
• The following Fiend Folio items are added to the Demon Swine Beggar pool:

Name	Icon	Weight	Description
Modern Ouroboros		1	Tears leave oil creep upon impact. Walking over oil creep will ignite it.
Sanguine Hook		1	Throwable hook that latches onto and pulls in enemies and pickups. Enemies become bruised while hooked. Releasing enemies makes them hemorrhage and launch bloody tears towards Isaac that hurt other enemies.
Pinhead		1	Luck-based chance to shoot sewing needles that pierce and inflict enemies with sewn. Sewn enemies link damage taken onto all other enemies with sewn.
Prank Cookie		1	Grants multi-colored tears with different status effects added in Fiend Folio.
Lil Minx		1	Spawns a pink Menace familiar that charges at enemies. Double-tapping the shoot button will have Lil Minx possess the nearest enemy and inflict them with berserk. Double-tapping the shoot button again will have Lil Minx exit the enemy and launch a spectral tear barrage. Berserked enemies periodically switch targets between Isaac and other enemies, deal and take bonus damage, move faster, and cannot die during the duration.
Toy Piano		1	22% chance, scaling with luck, to fire tears that doom enemies. Doomed enemies gain a counter that goes down every time they take damage. Upon reaching zero, the enemy takes 5× Isaac's damage and the effect is removed.
Astropulvis		1	On use, destroys the closest Rock and turns it into a large ghost. Using the item again will detonate all large ghosts in the room.
Black Moon		1	Isaac's tears gain a dark red glow. Killing an enemy with these tears creates a glowing red cross that damages enemies in an area of effect. Enemies killed by the cross don't spawn another cross.
Risk's Reward		1	Can be used to reroll an item in the Treasure Room to one of a higher quality. This is achieved by traversing a unique Psionic Cluster and fighting the Hermit.
Lil Lamb		1	Spawns a familiar that charges to shoot an Ipecac projectile. When Isaac takes damage, has a chance to drop to the floor and target enemies automatically.
Deadly Dose		1	On pickup, spawns a Cyanide Pill. Cyanide Pills provide an all stats up, but will start a death timer that will kill Isaac after 60 seconds. Taking a pill that isn't a Cyanide Pill will cure it, removing the stats and stopping the timer. Increases the chance for Pills to drop on room clear. Pills that drop while Isaac is not under the effect of a Cyanide Pill can be replaced with Cyanide Pills.
Pet Peeve		1	Grudge familiar that moves around randomly and deals contact damage. Double-tapping a fire button will have the familiar charge in that direction.
Malice		1	Upon use, turns Isaac into a black fireball which charges across the room. This gives invulnerability, deals damage to enemies hit, and leaves a trail of black creep during the charge.

Icarus & Baptismal Compatibility

• Retribution features a set of mechanics that involve upgrading and downgrading enemies.
• These mechanics are usually referred to as:
  • Baptismal downgrades.
  • Icarus/Antibaptismal upgrades.

Enemy Upgrades and Downgrades

• Fiend Folio's enemies have full compatibility with Retribution's Antibaptismal upgrade and Baptismal downgrade systems:
  • Main article: Retribution Compatibility/List of Retribution Downgrades and Upgrades

• Fiend Folio also has a handful of enemies found primarily through the Antibaptismal upgrade system:
  • Main article: Upgraded Enemies

Other Compatibility

Among other things, the chance for an enemy to upgrade while playing as Icarus is modifed by the number of Black Hearts owned. However, Fiend Folio's Immoral Hearts will also increase this chance.

• While Black Hearts each increase the chance by 2.5% regardless of whether they are a full heart () or half heart (), Immoral Hearts will increase the chance by 0.5% for each half of a heart ().

Mod Compatibility Index
Revelations	Revelations Compatibility - Bertran Synergies (Bertran MOD) - Revelations Wiki
Retribution	Retribution Compatibility - Upgraded Enemies - Retribution Wiki
Genesis+ Septic Shock	Septic Enemies
Tainted Treasure Rooms	Tainted Treasures Compatibility
Sewing Machine	Sewing Machine Upgrades - Sewing Machine Wiki
Samael	Samael Compatibility
Fall from Grace	Fall from Grace Compatibility