Very rarely will the traveler come across the Nightmare; they live in but one location in the midst of Finaru, and that location is hidden to all but three individual. However, there comes the once-in-a-blue-moon instance that the Nightmare escapes this sacred area. Normally a peaceful creature, the Nightmare will become lost, confused, and eventually violent.
The Nightmare is a semi-ethereal equine, capable of traveling at speeds incomprehensible to the average man. Its teeth bite as Mythril spearheads; its mane is as thorns; its tail is as refined slicing wires. Because of its half-existence within the material plane, it often registers to the eye as nothing more than an ebony streak, perceived to be a shadow.
It is best to avoid these beasts at all costs. Even in their most violent of states, the Nightmare generally do not initiate attacks on a whim. Leave them alone, and they will leave you alone; provoke them, and you will surely perish.