A cloaked skeleton that guards its lair with teleportation magic
A crypt thing appears as a cloaked skeleton, but contrary to appearances, is not undead and cannot be turned. They reside in their lairs and never venture forth. A crypt thing will never attack first, they will always let the party attack before they do. If they are not molested they will leave the adventurers alone.
Crypt things speak common. If questioned about the disappearance of any comrades, they will say they were disintegrated.
OSRIC