The Binding of Isaac Wiki

In The Binding of Isaac, every object or room that has a chance of spawning an item (Boss Rooms, Golden Chests, etc.) has a specific item pool from which it draws, ensuring that the item obtained is appropriate.


When an item is to be created, it is selected from the corresponding pool. For example, a Secret Room will draw from the Secret Room Pool when it contains an item or an item is rerolled inside of it. Whenever an item is picked up, it is removed from the pool that spawned it; seeing the item will result in one copy of the item being removed. Depleting the Boss Pool will force the use of the Secret Room Pool; depleting all others forces the use of the normal Treasure Room Pool instead. Depleting the Treasure Room Pool to 5 items or less will cause it to be refreshed. In certain cases, however, the game will crash; this is because with items that are in both the Treasure Room Pool and another pool, picking that item up in the other pool, (e.g. My Little Unicorn in the Secret Room) will not remove it from the Treasure Room Pool, but will instead make it so that that item cannot appear in the Treasure Room Pool; therefore, touching more than 5 items that are in the Treasure Room and another pool in the other pool will prevent the Treasure Room Pool from being able to refresh and mean that the game will crash when it runs out of items.

Unique Item Pool Modification[]

In order to decrease redundancy, certain items can be removed from pools even if they are not picked up. In the list below, the first event prevents the player from obtaining the item that follows.

  • Using a Health Up / Down pill: <3
  • Using a Speed Up / Down pill: Wooden Spoon
  • Using a Tears Up / Down pill: Wire Coat Hanger!
  • Using a Range Up / Down pill: Mom's Lipstick
  • Finishing an Eternal Heart / Making a deal with Satan: Lunch
  • Obtaining Dead Cat: Dinner
  • Obtaining Sacred Heart: Spoon Bender
  • Obtaining Ipecac / Polyphemus / Mutant Spider: The Inner Eye
  • Obtaining Spirit of the Night / Dead Dove: Ouija Board
  • Obtaining Pretty Fly by using a Slot Machine or through a pill: Halo of Flies

Additionally, obtaining the Rosary will add seven copies of The Bible to the Shop Pool, and obtaining Dr. Fetus will add six copies of Mr. Mega and Bobby-Bomb to the Treasure Room pool.

Treasure Room Pool[]

Boss Room Pool[]

The first occurrence of every item in this pool is removed from the Treasure Room Pool.

Secret Room Pool[]

Shop Pool[]

The first occurrence of every item in this pool is removed from the Treasure Room Pool.

Golden Chest Pool[]

The first occurrence of every item in this pool is removed from the Treasure Room Pool.

When in The Chest, all chests spawn items from the Treasure Room Pool.

Devil Room Pool[]

Challenge Room Pool[]

Library Pool[]

Because the library has such a small pool, and it removes two items at a time, this allows for an exploit with the Dice.

Angel Room Pool[]

Items cannot be removed from this pool.