Drelb Guardian (Haunting Custodian)

Climate/Terrain: Dark, Subterranean
Frequency: Very Rare
Organization: Solitary
Activity Cycle: Any
Diet: Negative Energy
Intelligence: Average to Very (9-12)
Treasure: Special
Alignment: Neutral (evil)
No. Appearing: 1
Armor Class: 2
Movement: Fl 6 (B)
Hit Dice: 5+3
THAC0: 15
No. of Attacks: 1
Damage/Attack: 3-12
Special Attacks: Chill, 90% seems retreating
Special Defenses: hit only by magic weapons, reflects psionic attacks
Magic Resistance: None
Size: M (6’ tall)
Moral: 12 (Steady)
XP Value: 1,400

The Drelb are seen as black, vaguely man-shaped clouds that have no true substance, but tend to shape themselves with two upper limbs, a torso, and a head with two glowing red eyes. Most people who see them mistakenly identify them as wraiths, however unlike wraiths, they cannot be turned as undead.

Combat: The touch of a drelb is so cold that it causes those struck by it to lose all body warmth instantaneously, which causes not just the damage (3d4), but also causes the victim to fall shivering to the ground, dropping all items which he was holding (no saving-throw). Victims of this attack are unable to act until this chill passes, or 1 round.
When confronted by a cleric attempting to turn it,or if prey is hesitant, the cunning monster uses a trick of illusion. It causes its form to rapidly diminish in size while gliding smoothly forward. This is 90% likely to give the viewers the impression that the drelb is retreating, while it is actually moving up to attack.
Magic weapons are needed to harm drelb; silver has no effect, unless it is magicked silver, which causes double damage. Drelb also have the faculty of imitation and/or reflection of psionic power. All power used within 30 feet of the creature or any psionic attack directed at it is imitated or reflected back upon the attacker.
Habitat/Society: Drelb inhabit the Negative Material Plane, but evil-minded persons will sometimes call them to the Prime Material Plane to serve as guardians of hidden wealth or secret places, so whenever they are encountered on this plane they are guarding something. Magic which draws the drelb to the Prime Material Plane is likely to function only from sunset to sunrise; so, much like undead, drelb appear only in twilight or darkness.
Ecology: Drelb serve as protection only, summoning them is considered an act of evil as the life of an innocent must be taken at the time of calling them forth from their own dimensions. While this spell has been lost to time, the Drelb do show up often enough to suspect ancient evil forces of great power is behind each and every one of them. It is also known that the Drelb is considered a minor spirit in the negative material plane, and many more powerful beings from this negative plane are more apt to using them successfully then a creature native to this plane—but of course that doesn’t stop people from trying to call them.