Crystal Key#170

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.
• 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 unlocking if multiple Crystal Keys are held, e.g. from absorbing using Smelter, holding Mom's Box, having a golden Crystal Key. 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 an I AM ERROR Room.