Nightmares

"Counter move to the Drakeweight horses, these creatures come straight from the mouths of the 7 Circles, billowing brimstone the entire way up. They should be avoided at all cost. If it wasn't for their accursed growing population base in Vassalstar and Takarez.."
  Considered an invasive species in Vassalstar and Takarez, Nightmares are creatures whom are native to the 7 Circles, a former dimension-turned collapsed one. Nightmares, sometimes called hell horses or demon horses, were fiendish equines named after the terrible dreams suffered by those that encountered them. They were wicked creatures best known for serving as mounts under a variety of malevolent beings, including revenants, devils, demons, undead, and so on.   Nightmares were seemingly emaciated stallions, approximately 6 feet (1.8 meters) tall at the shoulders, with night-black coats. On further examination, however, their warhorse-like exterior was revealed to be entirely superficial. They had huge heads, fangs like vipers, stomachs that were suited towards carnivorious consumption rather than herbivorious and malevolent dark eyes often illuminated by red-hot flames, and they spouted orange fire when their nostrils flared. Wreathed in fire, their manes were wild and their tails unkempt, but they turned to cinders and quickly dispersed upon death.   Nightmares were callous and cruel creatures that stalked those they could victimize. They displayed hatred towards all life on the Material Plane and exhibited an infernal intelligence unseen in true beasts. Rather than simply murder their targets, they used their supernatural powers to strike terror in them first, making them fear for their lives and killing them once they were reduced to panicking wrecks. One of their favorite tricks was to allow their victims one last moment of feeling safe before suddenly reappearing, dashing their last remaining hope, and then striking the killing blow.   Nightmares can only be handled by individuals of the Evil allignment successfully. Otherwise they would refuse to be ridden, and try to kill the individual attempting to tame them, or flee if possible.   Though most Nightmares without wings, those with wings are exceedingly rare, and considered to be priceless. Why you ask? Because to reproduce, a nightmare needs to reproduce with a winged nightmare. The problem? They were hunted to near extinction. So, as such, there is just alot of immortal demon horses running around.