Feyr

A feyr, or fihyr, was a chaotic creature that was formed from the nightmares of ordinary denizens, and dormant magical energy. They were unknowingly created in large settlements, such as cities, where they fed off emotions produced by the populace. There were four distinct types of feyr: larval, lesser, common and great.

Great feyrs were extremely rare, as they were created by the joining of many smaller feyrs, which were already rare. These great feyrs, however, were extraordinarily terrifying, able to direct control the emotions of a person or creature. They drove mortals mad with fear and emotional torment.

Description
Feyrs were grim and vile to the human eye. They had up to five eyes, and their mottled iridescent hide was warped like the folds of a human brain. It typically had two large tentacle-like legs growing where a pair of ears usually would on a face. Its face was spread across its whole body, and its large mouths boasting several pairs of teeth.

Combat
Feyrs used their monstrously large jaws to attack. These were purely for attacking, as the monsters fed off of emotions, not typical food. As they were created by magical energy, feyrs could easily fear their enemies, but great feyrs could directly manipulate their emotions, similar to the wizard spell, emotion.

Great feyrs could also use invisibility, and exploit this to cast negative emotions (such as hopelessness) upon their enemies, without them knowing the source. They were immune to both magical and non-magical fear.

Common feyrs could be slain by sunlight (and thus didn't live long), but greater feyrs could not. This, as well as their high intelligence, would allow them to live for much longer.

Society
Feyrs were most likely to be found on their own, or in small groups. However, there were times when common feyrs combined into a highly intelligent, greater feyr. Common feyrs did not travel long distances, but the greater ones would, if lured by very strong emotional states. Greater feyrs preferred to work at night, in order to get their fill without detection.

Ecology
They were mainly found in large cities, with a presence of priests and wizards. Feyrs preferred highly populated areas, to feed and grow stronger. These aberrations would wreck havoc in such areas. Towns under siege, cival wars, and highly oppressed societies were some of the possible breeding grounds of feyrs. For example, in the late 14th century DR, the denizens living near Boareskyr Bridge felt that they were doomed by the chaotic crusade of Caelar Argent. The residual magical energy, as well as the negative emotions of the people, spawned a greater feyr.

Greater feyrs could make other creatures their familiars, by invoking terror into their minds.

Video games

 * Baldur's Gate: Siege of Dragonspear
 * Dungeon Hack
 * Eye of the Beholder III: Assault on Myth Drannor
 * Icewind Dale II

Magazines
Trading card
 * Dragon Magazine Annual 2000
 * Spellfire: Master the Magic