This creature looks like a man-sized flying manta ray, dark gray in color.
Mantari CR 1/2
Speed 5 ft., fly 60 ft. (good)
Melee tail sting +3 (1d6)
Space 5 ft.; Reach 5 ft. (10 ft. with tail)
Organization solitary or pack (2-4)
Mantari sustain themselves on a diet of rats, carrion, and subterranean plants, but prefer the taste of fresh meat – particularly humans and gnomes. Mantari appear as large manta rays, gray in color, with a long smooth tail that ends in a sharpened barb. The mantari flies silently through its underground world in search of prey, and when encountered, it is often hungry and immediately attacks.
The mantari attacks by slashing and stinging with its tail. Its preferred method of attack is to dive on its target from higher areas, gaining surprise with its sting.
Mantari from the Tome of Horrors Complete, Copyright 2011, Necromancer Games, Inc., published and distributed by Frog God Games; Author Scott Greene, based on original material by David Wormell.