Crystal Key is a trinket added in The Binding of Isaac: Repentance.
Effects[]
- Whenever Isaac clears a room, has a chance to unlock a neighboring Red Room.
- This effect can occur while Isaac is inside a Red Room.
Notes[]
- It's possible to increase the chance of a Red Room unlocking if multiple Crystal Keys are held, e.g. from absorbing using
Smelter, holding 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 has a chance to generate an adjacent Red Room.
- Rooms that are re-fought using the 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 I AM ERROR.
In-game footage[]
Keys
 The Binding of Isaac: Rebirth
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