Slasrath

Slasraths were horrific monsters created by the yugoloths to serve as flying mounts.

Description
Slasraths had long, worm-like bodies with manta-ray-like wings some wide. The mouth was small, lamprey-like, and located on the underside of the front. The tail was long, thin, and ended in a venomous barb. They were typically black in color, though gray and green individuals were also recorded.

Behavior
These monsters were nearly mindless, only interested in finding prey to eat.

Abilities
Slasraths had two major abilities: the edges of their wings were razor-sharp, capable of shredding both armor and flesh, and the barb on the end of their tails was venomous. They flew by means of innate magic rather than their wings.

Combat
Wild slasraths lacked the intelligence to use any tactics, instead simply diving down on potential prey from above and slicing with their wings until it fell.

Ecology
Slasraths were native to Gehenna, where most of them were kept in the service of the yugoloths as mounts- it was said they could carry even a nycaloth without slowing. The yugoloths used them either as aerial cavalry, or for a leader to ride above its troops. Slasraths required special harnasses for riding, but could still make their normal attacks while mounted, and were capable of gliding steadily enough to permit spellcasting by the rider.

Yugoloth training of slasraths involving magical charms, if not outright domination magic, as well as pain and strict discipline. The riders and trainers used whips and spurs to maintain their authority over the monsters, who were kept in stables shaped like huge, black domes when not in use. Rather predictably, the cruel yugoloths fed their beasts slaves, wounded slasraths, and yugoloths who had the misfortune to displease a superior.

Slasraths hatched from large eggs with a wingspan, and grew over the course of their lives to have a  wingspan; yugoloths didn't ride them until they had at least a  wingspan. Additionally, slasraths were immune to the awful effects of their native plane. Wild slasraths hunted and ate anything they could catch and kill, including linquas, barghests, yugoloths, and nightmares. They spent all their waking time hunting from the air, and landed to rest only briefly. While on the ground, slasraths moved slowly, like oversized worms.

History
Slasraths were originally a species of slimy, mindless, horrible worm found in Gehenna until an enslaved sorcerer called Jehanu the Flayed transformed them into monsters they were never meant to be, at the orders of an ultroloth. A handful of these original slasraths escaped, but most remained captives. However, while the sorcerer transformed their bodies, their minds remained largely unchanged.