Onsible's key

Onsible's key was an alteration spell that transformed a physical key to make it fit a targeted lock.

Effects
The caster had to touch both the key and the lock to cast this spell. The key to be altered had to be within a certain range of sizes compared to a key that would actually open the lock—no less than half and no more than double the size of the correct key. Once cast, the spell lasted for three minutes, allowing three attempts to open the lock. The minimum chance to succeed was two-out-of-three, but the odds were even better for more experienced casters. If any attempt succeeded in locking or unlocking the targeted lock, then the key became useless for the duration of the spell. That is, it took at least two castings of Onsible's key to unlock a door, pass through it, and lock it again.

As an added benefit, if the lock was trapped, magically or otherwise, the caster became aware of the existence of the trap at the moment the enchanted key touched the lock. This applied only to the caster of Onsible's key—handing the key to someone else to use did not confer this benefit to them and the caster was not warned. Nothing about the kind of trap was revealed, only its existence.

To the unaided eye, the enchanted key did not appear to undergo any change whatsoever, but the true shape of the key was temporarily altered by this spell.

Components
This spell required verbal and somatic components as well as an amount of steel greater in volume than the key being transformed. The steel could be in any form—a whole piece, multiple pieces, or shavings—but it was consumed in the casting.