From Hellgatewiki.com
These twisted fiends are the unliving remains of those unfortunates who were slain in their sleep. The bodies and faces of Nightmares are eternally contorted, reflecting the state of their minds and souls when the demons took control of them. Their anguish is what fuels their arcane attacks, making them frightening to see and a horror to battle.
Note: In game they are classified as Spectrals and have an Aura which you should stay out of if you're able.
Caste: Spectral
Rank: Lesser Demon
Subtypes: Tormentor
Special: Emits a poison aura with a huge radius. Must be killed to stop the poison drain.
Nightmares seem more like something from the Spectral caste than Necros, but who are we to quibble with classifications? Nightmares are basically stationary poison turrets; any character in range takes steady poison damage until the Nightmare is destroyed. It's not a big deal when you find one Nightmare by itself, but when there are several in a room, and lots of other monsters in the way, the steady poison drain can get quite treacherous.
One early quest in the dry River Thames area requires you to retrieve an object for a group of Cabalists, then aid them in killing the titanic Greater Demon Nightmare they summon up.
This monster type was profiled in the Evolution of a Nightmare feature.
