Avari - man-sized, batlike fiends that are rivals of
yugoloths for territory. Unfortunately, they are neither as powerful or
as numerous as the fiends and have lost much over time. Long ago, avari
dwelt in a large central community, but their many wars shattered their
unity, forcing them to live in isolated clan in desolate areas of the
planes. They dwell there in dank caverns filled with bats, and inhabit
similar environs when found on the Material Plane.
#101 - Creature Catalog III)[Gehenna]