Diabolus

Diaboli (singular: Diabolus) were a race of people native to the Demiplane of Nightmares, where they filled the same niche humans did on the Material Plane.

Description
Diaboli were vaguely humanoid in form, averaging about tall, but possessed goat-like legs, pointed ears, and small, vestigial horns. They also had long tails that ended in a barb. Their hands were mostly normal but they lacked the smallest finger, instead only having three fingers and a thumb on each hand. Diaboli had reptilian eyes that ranged from bright red to yellow in color. Their skin ranged in color from pale mauve or lavender to near-black violet. They had forked tongues. Diaboli varied in how much hair grew on their bodies: bare diaboli had no hair at all, common diaboli had more normal amounts of hair, and hirsute diaboli would also have course, goat-like hair growing from the waist down.

Abilities
Diaboli possessed darkvision. Additionally, their forked tongues provide an enhanced sense of smell.

According to some sources, diaboli were not effected by magic cast by creatures from the Material plane, and that diaboli magic likewise did not effect creatures of the Material plane. However, indirect uses of magic could be wielded against them, and magic used by other creatures from the Demiplane of Nightmares, such as neh-thalggu, feyrs, nagpas, and maelephants, still effected them.

Personality
Diaboli had a wide range of personalities among themselves, but by and large they tended to be rather chaotic, if benign; this manifested in the form of extreme absent-mindedness, mild to severe mood swings, wild bouts of creativity, and otherwise mercurial personalities. However, they strongly believed in the the ancient traditions and mores that held their societies together.

Combat
Diaboli martial technology and techniques were not as advanced as those of the cultures of the Material plane, but most were skilled with the trident. Additionally, diaboli could attack with their tail barb, which was mildly poisonous.

Society
Diaboli were native to the Demiplane of Nightmares, a place where the Region of Dreams brushed up against the Far Realm, and the latter plane leaked through and tainted the place. Because of this, some diaboli fled through the Ethereal plane to Material planes such as Faerûn, where they settled and built small, isolated communities.

On both their native plane and in their other settlements, diaboli had no form of government, instead practicing a form of anarchy that is limited only by traditional customs, taboos, and a strong sense of fair play. They rejected all forms of government because they could not prove any one form of government as being better than the others.

Diaboli settlements were built in a strange, haphazard manner, without any apparent consideration for either defense or ease of navigation. The buildings themselves resembled ruins, with leaning stone walls and protruding beams and timbers. Various colors of paint in random splotches provided some form of camouflage from a distance.

Diaboli societies spared no amount of either wealth or energy on developing either philosophy or art. They were very generous and tolerant among themselves. However, diaboli innately feared humans and most other humanoids, and viewed humans as hideous demons or devils. Communication with others never when further than cool politeness.

Diaboli spoke their own language, called Diabolan. This language made frequent use of harsh, guttural hisses and the unique physiology of their forked tongues, making it difficult for most humanoids of the Material plane to learn. Most words contained soft "f", "s", "th", and "z" sounds, among other, stranger, ones. However, the same physiology that made it difficult for humanoids to learn Diabolan also made it difficult for diaboli to learn Common, and even those that did manage spoke it with a thick, serpentine accent. Typically, a diabolus might learn Abyssal, Common, Draconic, or Infernal. Additionally, diaboli had a tail code, a method of communicating simple ideas through the positioning and twirling of their tails.

Diaboli had no established religion, instead revering ideas such as anarchy, chaos, freedom, and wonder. Clerics existed, though they were very rare.

The neh-thalggu occupied a place in diabolus legends similar to the one dragons held in human legends. Diaboli regarded neh-thalggu as creatures of great power, cunning, and inscrutability. Additionally, neh-thalggu were some of the few creatures whose magic could effect a diabolus.