Drelb (Medium Monstrosity - CR 2)

Skulking on the pages of the AD&D 1st Edition Monster Manual II, I went through a stage, back in my youth, of using these waaaaay too much. Indeed, it got to the point that my players just assumed any wraith was actually a drelb, and laid into it with enchanted silver.

A manifestation of negative energy given hateful consciousness, these bizarre and incredibly rarely encountered entities are a nightmare for those unaware of what they are. Worse, even once their true nature is revealed, they have enough odd abilities and tricks to keep any group on their toes.