The Haunt

The Haunt is a boss that can appear:
 * In and the.
 * Only in.

Behavior
Phase 1 The battle begins with three Lil' Haunts circling The Haunt, who floats around the room and is invulnerable. The Haunt its and Lil' Haunts can still do contact damage to Isaac while incorporeal.
 * One Lil' Haunt becomes corporeal and chases Isaac. Once the first one is dead, the other two take up the chase.
 * Once all three Lil' Haunts are dead, Phase 2 begins.

Phase 2 The Haunt, now vulnerable, quickly flies to the upper wall of the room and begins to move left and right along the wall while periodically performing the following attacks: During The Haunt's transition to this phase, it can deal contact damage during the dash to the upper wall. The Haunt attacks based on its location and distance. If it cannot make it to a certain position, it gets stuck attempting to reach it and will not attack until it can resume moving.
 * Fires a straight laser downwards.
 * Fires five blood shots in a spread downwards.
 * If Isaac is close to the upper wall, The Haunt will quickly dash toward his position.

During both phases The Haunt deals a whole heart of contact damage.

Champion Versions

 * Black: Only two Lil' Haunts circle The Haunt in the first phase. In the second phase, The Haunt spawns 1-2 Spiders instead of firing a brimstone laser.
 * Pink: Only one Lil' Haunt circles The Haunt in the first phase. In the second phase, The Haunt has 50% less HP (100). The Haunt's laser is replaced with two diagonal Brimstone lasers that reflect once off of walls. The Haunt's blood-shot attack is changed to 8 shots and is aimed towards Isaac.

Trivia

 * It is the boss version of the Lil' Haunts.
 * The Forsaken is the posthumous version of it.
 * The Haunt's design may be a reference to Paunchy Chops, a boss from the game Gish, also developed by Edmund McMillen. They function similarly in that they are both ghosts that can phase in and out of corporeality, and they bear similar facial expressions.
 * The Haunt has a resurrected variation known as the The Heretic.