The Nightmare is a fiend/nightmare-type enemy from Final Fantasy XII. It can be found in the Phase 1 Dig area of the Henne Mines. Nightmares can teleport, and the party cannot attack them in mid-teleport; if a party member attacks one in mid-teleport no damage will be done.
Being a nightmarish equine creature, living in deep forests, possessing strange external organs that twist and wind like snakes. Though they have the bearing of herbivores at first glance, the positioning of their eyes and the set of their musculature are those of the flesh-eater, and indeed their teeth are sharp, being made for the tearing of tendon and hide. They are relentlessly aggressive, never abandoning a pursuit once the quarry has been sighted.
The uncharted wooded marches known as the Forests of Chaos are spoken of in legend, and though many are said to exist, little is known of their actual location. These dense forests, where the snowflies foregather in great flurries, brushing against the faces of all who pass, are so named because the sound of the snowflies' whirring wings pitch even the halest of wayfarers into confusion. They wander, lost, never again to leave the forest. While the marches may hide countless treasures, they are also places of unknown and unknowable danger. Consider your future, wayfarer. Consider your fate, and venture not into such places.