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An item pool is the set of items that can be generated under a given circumstance. There are many item pools that exist within The Binding of Isaac: Rebirth.

Item Weight[ | ]

Weight Decrementation[ | ]

  • When you see an item spawn, the weight of that item is automatically decremented inside of the respective item pool. However, the amount of the decrementation varies depending on the specific item pool.
  • If an item happens to be in more than one item pool, the weight decrementation will also apply to other pools.
  • Touching an item will remove it from all item pools.
  • If a pedestal cycles between multiple items, such as from (in Repentance)Collectible Glitched Crown iconGlitched Crown, each item option will count as being seen.

The following item pools are decremented by 50% (0.5) on sight:

The following item pools are decremented by 40% (0.4) on sight:

The following item pools are decremented by 10% (0.1) on sight:

All other item pools not listed above are fully decremented on sight.

Examples[ | ]

  • All items in the Treasure Room pool are completely decremented on sight. Thus, seeing a Collectible Notched Axe iconNotched Axe in the Basement 1 Treasure Room will make it impossible to spawn another Notched Axe in the run. (In this case, players do not have to touch the Notched Axe in order to prevent the game from ever spawning another one.)
  • (except in Repentance) All items in the shop pool are decremented by 0.5 on sight. Thus, if you use a Restock Machine to reroll a Collectible Treasure Map iconTreasure Map, you have a chance for another Treasure Map to appear. However, after the Treasure Map has already appeared twice on a run, it is completely decremented from the shop pool and it will never appear again.
    • (in Repentance) All items in the shop pool are fully decremented on sight. Thus, if you use a Restock Machine to reroll a Collectible Treasure Map iconTreasure Map, it will never appear again for the rest of the run.
  • If the player sees Collectible Telepathy for Dummies iconTelepathy for Dummies in the Basement 1 Treasure Room, it is completely removed from all other pools for the rest of the run even without touching it. Seeing it in a Library and not touching it, however, allows it still to be encountered as a Treasure item, with slightly lowered weight.

Unused Item Pools[ | ]

In the itempools.xml file, we can see that there are some unused item pools:

Set Drops[ | ]

The set drops are as follows:

From the Seven Deadly Sins:

From Bosses:

From Machines:

From Rocks:

From ShopkeeperShopkeepers:

From Items and Trinkets:

From Rooms:

(in Repentance) From Boss Bumbino ingameBumbino after he collects 12 cents:

(in Repentance) Chance from Boss Hornfel ingameHornfel after defeating his 2nd phase before he escapes:

(in Afterbirth † and Repentance) From sacrificing familiars with Collectible Sacrificial Altar iconSacrificial Altar

Notes[ | ]

  • Item pools can be exhausted by having the game create every item in that specific pool. Items do not need to be picked up for this to happen, the game simply has to generate them (rerolling the item with Collectible The D6 iconThe D6 for example).
    • When an item pool is exhausted, the game will generate items from the Treasure Room pool instead.
    • If the Treasure Room pool is exhausted, the only item that can be generated from it is Collectible Breakfast iconBreakfast.
  • Even though you technically cannot see items during Curse of the Blind, their weights are still being reduced upon encountering them.
    • (in Repentance) The same applies to blind items in alternative chapters.


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