Rotgut

Rotgut is a boss added in The Binding of Isaac: Repentance that can appear in the Corpse.

Behavior[ | ]

Phase 1[ | ]

The first phase occurs against Rotgut's "face" in its regular boss room. Rotgut is stationary in the center of the room and performs the following attacks:

Spews a constant wave of projectiles that alternates above and below it in a fanning pattern.
Spews out waves of fluctuating spaced-out projectiles in a disorganized pattern.
Fires rings of 8 expanding projectiles that alternate between rotating clockwise and counter-clockwise.
Fires three waves of projectiles in a row:
- A radial of tightly knit slow-moving tears.
- A radial of spaced out fast-moving tears.
- A burst of randomly positioned tears that hover for a moment before dropping.
Coughs up a horizontal burst of red projectiles to the left and right side of itself.
Vomits out projectiles, bones, as well as Globin goo, Gazing Globin goo, and Small Maggots that rain down in a large area.

Phase 2[ | ]

Once Rotgut's first form has been defeated, it sucks Isaac, any monsters, and floating projectiles into its mouth and sends Isaac into a Crawl Space-like interior. The second phase consists of a large maggot that sits in the bottom right of the room and performs attacks depending on Isaac's position.

If Isaac is on the platform, the maggot uses its rear end:

Launches a cluster of projectiles onto the platform and covers it in green poisonous gas.
Launches an Ipecac shot that bursts into arcing tears.
Shoots out 6 slow travelling tears that travel in a wave pattern across the entire room.

If Isaac is below the platform and on the ground, the maggot uses its head:

Spits out a stream of arcing blood projectiles along with a few Attack Flies and Small Maggots.
Shoots out a Brimstone laser.

Phase 3[ | ]

Defeating the Maggot allows passage into the next chamber, which contains Rotgut's "heart". The heart switches randomly between two modes of projectile patterns that occur for the entire duration of the fight:

Mode 1: shoots out half-rings of 6-7 green projectiles below it with each pulse of the heart.
Mode 2: drops 3 yellow projectiles in random locations with each beat of the heart. Each projectile splits into 2 arcing projectiles after hitting the ground.

The heart can perform additional attacks that occur independently of its two set modes:

Retreats upwards and spawns Leech on the end of the room furthest from Isaac. These Leeches move quickly across the screen and despawn upon reaching the edge of the screen. The final Leech spawned has a chance of being an Adult Leech.
Drops 2 large blood projectiles below it one after another. Each bursts into smaller projectiles that bounce all over the room.

After defeating this phase, Isaac is automatically ejected out of Rotgut's insides and back into the boss room.

Gallery[ | ]

Rotgut in-game.
Gus: the giant Maggot in Rotgut's second phase.
Rotgut's third phase.
Rotgut's original splash art in Antibirth.
Rotgut's first phase in Antibirth.
Rotgut's third phase in Antibirth.
Rotgut concept art.

Notes[ | ]

Dying with a respawn item (such as Dead Cat) in the second or final phase places Isaac in the previous phase, meaning Isaac has to fight that phase again.

Trivia[ | ]

Compared to Antibirth, Rotgut's 1st and 3rd phases have a new visual design.
- Rotgut's appearance change was a decision made by Edmund.
The maggot inside of Rotgut has been nicknamed "Gus" by the developers.
- Tainted Spitty, an enemy which can appear during the Ascent to reach Home, bears a strong resemblance to Gus in both appearance and attack patterns.
Rotgut is the informal name for a grade of moonshine that is very poor quality, being poor enough to be deadly to drink.
Rotgut is the name of a level from Super Meat Boy, one of Edmund McMillen's earlier games.
Rotgut's current depiction is explained by a developer to be possibly a huge Fatty fused to the floor, although it also may be a posthumous variation of It Lives. However, there isn't too much evidence about this.

Bugs[ | ]

Bug!

If Isaac is small enough (with for example), he can very easily clip through the ground during the Rotgut fight at phase 2 or 3 and enter I AM ERROR room, consequently skipping the fight to Corpse II.

Dashing through the Maggot in phase 2 using items such as Mars or A Pony can also clip Isaac through the room, causing the same effect.
This is also possible when Suplex! against its second or third phase.

Bug!	If debug 10 ("quick kill") is active, Rotgut will get repeat its phase 1 death animation indefinitely, preventing Isaac from accessing phases 2 and 3, thus softlocking the game.

Bug!	If Suplex! is used to kill Rotgut's first phase, the fight will fail to progress as instead of taking Isaac to the next phase touching Rotgut will hurt him.

Bug!	A softlock can occur if a Giga Bomb is used to kill Rotgut's first phase while destroying a tile under his location. Rotgut will constantly try to inhale Isaac, but since there is a missing tile under Rotgut, Isaac will never be able to enter the 2nd phase crawl space unless Isaac has Flight available.