You open one of the 1002 boxes on this floor and find...

The Philosopher's Shotgun. This is an old-fashioned double-barreled shotgun with strange runes carved over the barrels. Lead shot fired from this gun is specially conditioned for the following 3d6 minutes - if it is embedded in the flesh of a living sentient creature, it will turn to gold if that creature dies before the duration expires. A bloodstained lab book in the bottom of the crate describes the (occult) creation and operation of this gun. Interestingly enough, the creator thought of it as a failure - he wanted it to grant immortality to those it shot.