Buck
Buck is a boss in the Fiend Folio MOD that can appear in the 
Basement.
Behavior
Buck remains stationary and will cycle through the following attacks in the following order:
- Grabs a sack from behind him and shoots 2 streams of bloody projectiles towards Isaac: one slow-moving but travels further, the other fast-moving but arcs higher with less range. He will repeat this attack multiple times with a small pause between each stream to redirect his aim at Isaac while also allowing for space to weave through the barrages.
- Within the stream are some larger projectiles that deal a whole Heart of damage.
- If a Lez is alive during this attack he will aim some of the projectiles barrages towards her.
- Summons a Lez and a
Snagger at the same time in random locations near him. - He then tosses a
Bomb to the Snagger, and a Bomb or a large bloody projectile to the Lez.
- He will always perform this attack immediately after summoning his minions, and will repeat it in-between all other subsequent attacks as long there is at least 1 Snagger alive. If there are 3 or more spawns alive then Buck can throw 3 Bombs/projectiles to randomly selected spawns.
- Snaggers will catch and throw the Bombs thrown by Buck before they ignite, and can choose to either throw it towards Isaac or into a Lez's mouth if she has it open.
- Takes off his sack head, and shadowy limbs from inside the bag will begin to rummage around and toss out the following contents at random, up to 3 times in a row:
- 4
Attack Flies. - Numerous scattered blood projectiles.
- 3 Bombs which ignite after they touch the ground.
- 4
Occasionally, if Isaac is close to Buck, he will pause any other current attacks and make an aggressive swipe towards Isaac, launching himself forwards a short distance. He will then resume any previous attacks he cancelled.
Notes
- Buck is immune to damage from his own Bombs.
- There is a maximum of 3 Lezs that can be alive at once. There does not appear to be a cap on Snaggers.
- Isaac has a short window to pick up any Bomb tossed out by Buck once it hits the ground, as long as none of his spawns reach it and before the Bomb automatically ignites.
- If Isaac has
Humbleing Bundle, Buck has a chance to toss out 
Double Bombs from his head sack. Although they will explode like single Bombs, if a Snagger picks one up, it will be turned into a Double Bomb and the Snagger will throw out 2 Bombs.
BOGO Bombs will turn all Bombs thrown from his head into Double Bombs.
- If Isaac has
Sack Head, the bombs Buck tosses from his head sack have a chance to turn into various 
Sacks once they land on the ground. - Using
Bag of Crafting to deal the killing blow to Buck will cause him to drop the 
Mystery Badge.
Spawns
Lez
Lez is a special enemy only summoned by Buck, and cooperates with him in a variety of ways to attack Isaac. While waiting for Buck to perform an action, she will usually sit in one place and occasionally hop towards Isaac.
Lez will have her mouth open indicating that she is ready to assist Buck in the following attacks:
- Buck will directly toss a Bomb or large bloody projectile towards Lez, who receives it.
- While Buck is firing projectiles from his sack, he will aim one or two of the barrages at Lez, who will try to catch some of them as they travel.
- While Buck is lobbing flies, projectiles, and bombs from his head sack, Lez can catch some of the projectiles or Bombs.
If Lez has something in her mouth, she will perform one of the following actions based on the object:
- If she catches some regular projectiles in her mouth, she will then fire up to 5 bloody projectiles towards Isaac, one at a time.
- If she has a Bomb in her mouth, she will hold it for a period and will choose to either spit it back out towards Isaac, or hold the bomb in her mouth and hop after Isaac, exploding when near him and killing herself in the process.
- If she has a large bloody projectile in her mouth, she will hop towards Isaac before biting down on it and shooting 8 projectiles around herself.
Notes
- Lez is fully immune to Buck's bomb explosions while her mouth is open to "catch" something, and takes reduced damage from them in all other scenarios.
Video Showcase
Trivia
- Buck was originally named "Big Bandit".
- If Isaac dies and gets a Game Over against Buck, Buck can be heard laughing and then spitting on Isaac's corpse in disrespect.
- "Once I was a Cuck but now I'm a Buck" is Buck's signature catchphrase, according to the developers.
Delirium is able to transform into Buck, and has a unique coloration when doing so.- In the bottom-right corner of Buck's spritesheet in the files of Fiend Folio exists a sprite of Buck making a circle with his hand and the word "epic" drawn next to it, in reference to "the circle game".
Gallery
Buck without eyebrows, prior to drawing them on at the start of the fight.
Buck rummaging through his sack, partially revealing his true form within.
Delirium's appearance while transformed into Buck.
Lez holding a ball of blood.
Lez holding a bomb.
Drawing of Buck in the Bestiary and on Isaac's last will.
Buck's health bar icon if Enhanced Boss Bars is installed.
Sprite of Buck making the "circle game" gesture.
3D Render of Buck.
Old portrait of Buck.
Placeholder portrait of Buck.
Placeholder sprite of Buck.
 Bosses 
| |
|---|---|
| Chapter 1 | Buck - Honeydrop - The Whispers - Griddle Horn - Buster - Meltdown |
| Chapter 1.5 | Ghostbuster - Cacamancer |
| Chapter 2 | Battie - Kingpin - Slinger - Monsoon - Aquagob |
| Chapter 3 | The Organization - Gutso the Great - Luncheon - Pollution - Tsar - Junkstrap |
| Chapter 3.5 | Warp Zone - Dusk - Madomme |
| Chapter 4 | Basco - The Sun - Peeping - Cacophobia |
| Chapter 4.5 | Mr. Dead |
| Minibosses | Psion - Gravedigger - Hermit |
| Vanilla Boss Champions | Golden Plum - Ghost Larry Jr. - Mucus Monstro - Technopin - Albino Widow - Beehive Fistula - Possessed Hollow - Wine Husk - Kidney of Infamy - Alien Loki - Fiend Mom - Alien Lokii - Grinch Krampus |