Bone Key

Effects

 * Opens anything related to doors and locks in the room, as well as every other room for the remainder of the floor.
 * Opens closed doors.
 * Unlocks the door that leads to Mega Satan boss.
 * Opens Boss Rush, even if timer has already passed 20 minutes.
 * Opens Blue Womb, even if timer has already passed 30 minutes.
 * Allows to escape Mom.
 * Opens chests and key blocks.
 * Opens Challenge Room and Boss Challenge Room doors from both sides.
 * Grants access to black market in Crawl Space.
 * Opens the exit room door in Greed Mode.

Interactions

 * Bone Key can be used in the starting of a floor to move across rooms without worrying about killing enemies in order to clear rooms.
 * Bone key can be also used strategically after exploring the floor to see if worth using at it.