In-game pickup line
“Call to the other side”
Mechanics
What Crystal Key does
- Each room clear has a one-in-three chance to generate a Red Key room.
- The chance is lower when the room just cleared was already a red room.
Achievement #569
How to unlock it
Defeat Mother as Tainted Lost.
Unlocking an item and finding it during a run are separate steps.
Explore more unlocksIn a run
Practical note
Take the extra door when the floor layout gives you time to explore before the boss.
Reference
Game data and sources
The trinket ID, icon, game-file tags, and short pickup line come from the extracted Repentance files. This effect explanation is an editorial summary checked against the references below. Repentance+ can differ.
