But not nearly as terrifying as The Orb of Hyper-Dysentery! Fortunately, most owners of treasure hordes avoid relying on such magic devices due to the mess they cause, but every so often you find one sadistic S.O.B. who takes a perverse pleasure in watching thieves having their stealthy movements exposed by, well, another kind of movement. That, and the emaciated corpses they leave behind can be an effective deterrent against other uninvited guests, though you have to contend with servants who might get a little resentful having to clean up the vault and its contents after a raid is thwarted in this manner. Oh, and make sure you turn the dumb thing off before you send the janitors in. Good help is so hard to come by so you don't want to lose it due to an unfortunate oversight.