Nightmares serve as mounts for powerful evil beings. Whilst in shape they resemble large warhorses, they are unmistakably otherworldly, having blood red eyes, fiery nostrils, powerful fangs, a midnight black coat, a mane of shadow and hooves that appear to leap aflame when they run. Though it is known that Nightmares can understand what their riders ask of them, they are not thought to be able to speak themselves; but they seem to be able to communicate with one another well enough.

Although most Nightmares do not possess wings, they can fly through the air considerably faster than they can run along the ground. Their capacity for such swift flight is greatly valued by those they serve, as is their ferocity in combat. Nightmares hate living creatures and, being given to viciousness, will generally attack any non-evil entity they encounter. They use their fangs to bite for 2d4 damage and strike with their hooves 1d6+4 damage, which will also set any flammable objects they strike alight. In their excitement, Nightmares are also known to produce a noxious smoke that causes anyone within ten feet to have to save vs paralysis or suffer a -2 penalty “to hit” and damage whilst in the vicinity.

Nightmares have a strong sense of purpose and this can make them difficult to control; it takes an iron will or powerful magic for a rider to perpetually retain mastery. It is thought that their services can also be bargained for, but exactly what evil such an agreement might entail is unknown.

If ridden by a creature weighing more than 100 lbs, the nightmare’s aerial agility level is reduced to III.