Nightmare (creature)

A nightmare is a neutral evil outsider from the Lower Planes that resembles a large black horse with flames wreathing its hooves, flowing forth in the shape of its mane and tail, and trailing from its nostrils and red eyes. A nightmare will sometimes serve a powerful evil creature as a mount. It possesses the ability to travel to other planes and a nightmare can bring its rider to one with it. A nightmare extends its resistance to fire to its rider. According to legend, particularly powerful nightmares can also carry their riders to and from the Shadowfell. If killed, the nightmare’s flames gutter out, leaving a mane and tail of ash that quickly disperses.