Editing Nightmare (section)

===Summoning nightmares===
Although it seems creatures of the lower planes can readily use nightmares as mounts, the Monstrous Compendium Outer Planes Appendix contains a rather convoluted process for Prime Material Plane residents to secure one as a mount. A wizard of at least 5th-level must start by casting a mount spell to attract the attention of the nightmare, followed by a monster summoning III spell, and then finally a wall of fog, after which a nightmare will come galloping out of the mists. Once this is done, anyone (not just the caster) can offer the nightmare oat-like flakes of platinum worth at least 200 gp in value to secure its services for 72 hours.

Apparently, this isn't the only way to call a nightmare into the world. Labyrinth of Madness has a statue which uses a special version of monster summoning to summon various monsters, include a nightmare. In the article Pleasant Nightmares! in Dragon #186, a nightmare haunts a castle built on an ancient evil unholy spot. Its appearance can be stopped using an exorcism spell, but this only works half of the time.

In 3rd Edition, the core spell Lesser Planar Binding, combined with a Dimensional Anchor and Magical Circle Against Evil, can call a Nightmare to negotiate with (or, as mentioned above, immediately slay to reanimate as a skeleton). Despite this, the The Book of Vile Darkness has a call nightmare spell. It is a demonologist spell, but is also available to sorcerers and wizards. The summoned beast remains in service for a week, or until the caster moves more than 150 feet away from it. The catch? The material component for the spell is a soul! If a soul seems a high price to pay, the alternative summoning rules in The Summoner's Circle in Dragon #302 allow a spellcaster to expand the list of creatures summonable using summon monster V to include a nightmare with only a few days of research.

Also worth a mention is the conjure nightmare spell from Dragon #221. This spell summons a nightmare which serves willingly as long as it is given only evil tasks to do. It will rebel if given tasks that do not have an obviously malicious purpose. The spell is quite expensive to cast, requiring 200 gp of platinum flakes. More importantly, the nightmare is not summoned from the lower planes, but from the Plane of Dreams, where it is plucked from a random sleeper's nightmares. This means that the nightmare only remains summoned until that sleeper awakens, which could prove rather inconvenient, since the caster has no control over which sleeper's dream the nightmare is plucked from.