Aetheric Irritant

An aetheric irritant is a chime that can emit a subsonic frequency that otherworldly beings find unpleasant. When you Activate an aetheric irritant, you sound the chime and place it on the ground in a square within your reach. Creatures with the fey, spirit, or undead traits must attempt a Will save when they enter the affected area and at the beginning of every turn they are in the affected area. Those who fail the save treat the area as difficult terrain until the beginning of their next turn. A creature that critically succeeds at the save is immune to all aetheric irritants for 24 hours.