Reap Creep

Reap Creep is a boss added in The Binding of Isaac: Repentance that can appear in and the, as well as in the  in the alternate path.

Phase 1
Upon spawning, Reap Creep jumps up to the top of the Boss Room similarly to The Haunt. It starts off taking Wall Creep's form and can perform the following attacks:
 * Spawns a Wall Creep on either the left or right wall.
 * Spews out a continuous stream of projectiles vertically while attempting to follow Isaac's movements.
 * When reaching near the end of either wall, it leaves a gap between the stream and the wall.

Phase 2
After taking enough damage, Reap Creep takes Blind Creep's form and has new attacks:
 * Spews a huge number of disorganized projectiles, similar to Monstro, but larger.
 * Spews out a wide spread of spaced projectiles.
 * Spawns 3-4 spiders or a Trite downwards.

Phase 3
After taking enough damage, Reap Creep takes Rage Creep's form and has new attacks:
 * Slams itself against either the left or right wall, causing rock projectiles and 3-4 Spiders to fall from the ceiling.
 * If it's fought in the Mines, 3-4 Rock Spiders fall instead.
 * Charges for a moderate period of time before shooting a wide laser while attempting to follow Isaac's movements.
 * When reaching near the end of either wall, it leaves a gap between the laser and the wall.
 * Charges for a long period of time before shooting 4 regular Brimstone lasers diagonally outwards while attempting to follow Isaac's movements. The beams slowly come together leaving a small gap within the center.
 * The two Brimstone attacks have distinct charge sounds, allowing the player to distinguish them.

Trivia

 * Originally in Antibirth, killing it, Baby Plum and The Pile were necessary to unlock Antibirth's alternate chapters.
 * Reap Creep is one of two bosses that can appear in both the main path and the alternate path, the other being The Pile.
 * Because of this, its battle theme will be different, depending on where it's fought. If it's fought in The Depths or the Dank Depths, either Crusade or Cerebrum Dispersio will play, while if it's fought in the Mines, Juggernaut will play.
 * It is the boss version of Wall Creeps.