Binding of Isaac: Rebirth Wiki

Added in Repentance

Crystal Key is an unlockable trinket added in The Binding of Isaac: Repentance.


  • Whenever Isaac clears a room, has a chance to open a neighboring Red Room Red Room.
    • This effect can occur while Isaac is inside a Red Room, but the chance is smaller.


  • It's possible to increase the chance of a Red Room Red Room unlocking if multiple Crystal Keys are held, e.g. from absorbing using Smelter Smelter, holding Mom's Box Mom's Box, having a golden Crystal Key, or other methods. The chance for a Red Room door to unlock depends on the number of Crystal Keys held and if the room cleared is normal or Red.
Crystal Key Count Normal Room Red room
1 33.3% 12.5%
2 50% 16.6%
3 100% 25%
4 100% 50%
5 100% 100%
  • Each cleared wave of a Challenge Room Challenge Room has a chance to generate an adjacent Red Room.
  • Rooms that are re-fought using the D7 D7 have a chance to generate additional Red Rooms.
  • Doors do not have to open to an actual valid Red Room, and can lead outside the map and into an I AM ERROR I AM ERROR Room.

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