Crypt thing. This creature is a necromantic guardian set in place by a wizard or priest of at least 14th level to secure a crypt, graveyard, or tomb. The creature's teleportation attack can be quite disorienting and frightening to opponents, and most often, crypt things act more as deterrents than physical threats. Unless the necromancer or priest has chosen a tomb or crypt as a lair (or stores something valuable in such a location), a crypt thing is unlikely to be a popular topic of research for that particular spellcaster. Kazerabet hardly gives them more than a passing reference in her Art of Necromancy, and the Book of Shadows is little more informative.