Divination Key

Wondrous item, uncommon

This key has a jagged crystal ball shard embedded in its end. While the key itself doesn't unlock any doors, it has 3 charges for the following properties, and it regains 1d3 expended charges daily at dawn.

Keyhole Clairvoyance. You can use an action to insert the key into a keyhole and speak its first command word, expending 1 of its charges. When you do, you become blind with regard to your own senses, but can see through the other side of the keyhole (if any) as if you were on the other side of the lock. This effect lasts until you remove or let go of the key (no action required), at which point your senses return to you.

Lock Scrying. You can use an action to tap the key to a lock and speak its second command word. When you do, a minuscule emblem of an eye appears on the lock where you tap it. If a creature uses its action to examine the lock, the creature can notice the eye with a successful DC 13 Intelligence (Investigation) check. The eye remains for 7 days, until it's dispelled, or until you use this property on a different lock. While the eye remains, the divination key magically vibrates whenever a key or lockpick is used on the lock. Furthermore, while the eye remains on the lock, you can use an action to touch the key to your forehead and expend 1 of its charges. When you do, you become blind and deaf with regard to your own senses, and you can see and hear as if you were in the lock's space, looking outward from the lock on the side that bears the eye. At the end of your next turn, this effect ends and your senses return to normal unless you expend an additional charge to extend the effect for another round.

For our discerning, arcanically inclined clientele, a tool like this speaks for itself, perfect for both acquiring and preserving your ill-gotten gains. But, to those unconvinced, I can say this: if you've ever been poked in the eye by a watcher (or even a clever trap!) on the other side of a keyhole, know this will keep your precious peepers out of harm's way!
—Review from Threadfoot's Journal for the Discerning Thief