Rath'shak

Rath'shak were bestial creatures that only lived in and around Í Núvilvor, or the Cloud's Teeth. They each had the head of an eagle, a grey furred body, three scorpion tails, two pairs of wings, and an eagle's claws. They were extremely hostile to everything that moved, especially 'earthcrawlers' as they called anything that couldn't fly.
They ate any meat they could get, apart from grákh snakes, which were deadly when consumed, due to their consumption of the root of the palloka tree. The Rath'shak even ate each other when the were hungry enough, as well as the dragons that also inhabited the floating mountain range.
The three scorpion tails that a Rath'shak possessed each performed a different function, although the bulbs on the end all injected venom. The tail on the right side contained a paralysing agent that worked by injecting the chemical succohylodrine into the victim's body. The chemical shut down the nervous system, resulting in a loss of movement, as well as loss of most sense. However, elves were resistant to the drug, and dragons were immune altogether. The tail on the left held a quick-acting poison, which killed victims within minutes, if not seconds. The tail in the middle contained pressurised ziroltu oil, an acid that burned like fire when it came into contact with any living thing. When attacking with the middle tail, the Rath'shak conctracted muscles around the base of the venom bulb, which forced the oil out of the tip. When their supplies of oil were depleted, they naturally produced it within their bodies. This ability made them prized by mercenaries, bounty hunters, and rebellions alike. Only one other creature in the Kingdoms had the ability to produce the ziroltu oil like this, and it was the kurunani, a species of draconic creature from the Rift.
The dragonriders had an encounter with a Rath'shak named Nargoroth, who they killed after he pursued them beyond Í Núvilvor. It was then that they met a Ranger, who led them back to the Castle, which was under siege.