Skeleton Key

Effects
This intricately forged key, in something that threw Warehouse Agents for a loop, can open any door - as long as that door is a closet door. Once the door is open, any person who steps inside has access to the answers of any secrets they wish to know about. Unfortunately, the key requires that the user shares its ultimate secret with the closet - namely, their skeleton - when they leave the room.

The door to the closet can remain open during this process, however, so information can be relayed to those outside of the door, and no matter how many people are brought into the closet, the key only requires one skeleton, so theoretically one can avoid losing their calcium-enriched structural supports when using this key (as one particularly insane owner of the key proved). But someone is losing some bones, that is certain.