Crypt Thing

Shreds of leathery flesh cling to this skeletal figure’s body, while twin motes of fiery light glow deep in its eye sockets.

Source: AD&D 2nd Edition Monstrous Manual. Originally from AD&D 1E Fiend Folio.

     Crypt Things are undead creature who guard tombs, graves, and corpses. The sole purpose of this guardian is to protect those who have been laid to rest. They are not your typical evil guardian but neutral in nature. It only animates when a grave robber/adventurer have disturb the sanctity of their lair. Until that point they lay motionless and appear as nothing more then a cloaked skeleton.

     Once animated they spring into action. Their main line of defense is to teleport offenders away from their lair. They have been known to teleport an adventurer directly over a pit or chasm which usually ends in their unfortunate death. There are two types of Crypt Things ancestral and natural. Ancestral Crypt Thing are not created but mysteriously appear when someone of significance needs protection. Natural Crypt Things are created by wizards or priest to guard an important tomb. 

Combat: Crypt Things are worth 975 experience. Once it has exhausted it's teleportation trick it resort to a claw attack that deals 1d8 points of damage.  

-Teleportation: Once per adventuring group the Crypt Thing can teleport them in a random direction. Each character is allowed a saving throw vs spell to resist this effect. The victim won't appear inside a solid object but they don't necessarily appear on level ground. They can appear several hundred feet in the air and fall to their death. The following table is used as a guideline or can be rolled randomly if you choose. 

1d100	Destination
01-20	1d10×100’ north
21-40	1d10×100’ east
41-60	1d10×100’ west
61-80	1d10×100’ south
81-90	1 dungeon level up
91-00	1 dungeon level down

-Immunities: Only magic weapons can deal damage to a crypt thing, Like most undead they are immune to mind-affecting effects. The magic that binds them to their lair makes them immune to turning. 

-Vulnerabilities: They are harmed by Holy Water and Holy Symbols.

     It is rumored that the powdered marrow of the Crypt Thing can be used to create a potion of undead control. The bones of the Crypt Thing can be used to manufacture pipes of haunting that imposes -2 penalty to saving throws and is twice as effective.

     The Crypt Thing makes a great guardians. A city with a large Necropolis could have an entire order of Crypt Things protecting it. Since they are intelligent undead they can be used as the keepers of the catacombs. Maybe a great artifact is lost in the catacombs and the final confrontation is against one of these undead. 

     Another option is the adventurers have reached the Crypt. They face multiple Crypt Things. The group fails it's saving throws and is teleported to a secret dungeon level which they must brave to get back to their original destination. The second time around the Crypt Things can't use their teleportation and the climax of the adventure can take place.