Downpour

Downpour is a new environment added in Antibirth.

Treasure rooms in Downpour always have two items to choose from.

After "A Secret Exit" is unlocked, a locked door to Downpour I or II will appear upon completing The Basement/Cellar I or II, respectively. The locked door requires a single key to enter.

Downpour resembles flooded sewers, with water reflecting the environment. Its enemies are water-themed and mainly shoot tears, like Isaac, instead of blood. Under certain circumstances, after killing all enemies in the room, several Gapers will emerge from the water to attack Isaac.

Downpour is the only one of the four new added chapters in Antibirth that can contain a Rebirth boss that isn't the Fallen (the Haunt).

Flooding & Storm
The Downpour features a heavy emphasis on water and flooding. The entire floor is submerged in a pool of waist-deep water, that some enemies such as Small Leeches and Striders are capable of using to swim over pits. Numerous Deep Gapers also hide beneath the water and emerged when all enemies in the room have been killed. The reflection visible in the water is also utilized by Wraiths, which they are always visible in even though they are invisible otherwise. There is also a storm playing out in the background, which when lightning strikes, brightens up the room and reveals any Wraiths in the room.

Ghosts
The Downpour is also home to many incorporeal elements as well. Appearing in this level are Polties and Mullighouls, along with the invisible, ghostlike Wraiths, in addition to the returning Rebirth boss The Haunt, which coupled with the darkened environment gives the level a rather supernatural feel.

Rebirth Monsters

 * Gaper
 * Frowning Gaper
 * Pooter
 * Fat Fly
 * Level 2 Fly
 * Lil' Haunt
 * Clotty

Knife Piece

 * Downpour II contains Knife Piece 1, one of three pieces necessary to enter the Corpse.


 * Somewhere on the floor, there will be a seemingly empty dead-end room with a minimap icon that indicates the room has a chest. Bombing the center of the room will open a hidden stone chest containing Knife Piece 1.

Music

 * The track that plays in Downpour is titled Hallowed Ground.

Trivia

 * Downpour is referred to on Isaac's Last Will as "Some Sewer".