Skeleton Keyring

DM: When you disburse this item, you should specify how many keys are on the keyring.  Roll 2d4 if you want to determine this randomly.

When a PC tries one of the keys to open a lock, roll 1d6 (this costs an action during combat). On a 5 or 6, the key fits the lock.  The keys can be tried in this manner one by one, but once a key's lock is determined, it cannot be used in future attempts.  The PC should track how many available keys are left on the ring.

During combat, if a PC wants to lock or unlock a lock for which they had already discovered the key, they must pass a DC 10 INT check. If they fail, they fumble around with the keys and try the wrong one this round. Clever PCs might somehow mark the keys to bypass the need for this check.