Diaboli, the plural form of Diabolus, are one of Dungeons & Dragons' most forgotten, and yet most ancient of races. Originally appearing in the Master Set for Basic D&D, they then went on to appear in the Wrath of the Immortals boxed set. They were then updated to Advanced Dungeons & Dragons 2nd edition when they were made official denizens of Mystara, courtesy of that setting's Monstrous Compendium Appendix. Finally, their journey culminated, so far, when they appeared in their own "Winning Races" article in Dragon Magazine #327, which not only updated their lore to 3.5, but also made them a playable race.
The diaboli are a race of benevolently anarchistic (Chaotic Good, with a small minority of Chaotic Neutral and tiny minorities of Chaotic Evil, Neutral Good, True Neutral and Neutral Evil) humanoids native to the Demiplane of Nightmares; a plane coterminous with the Region of Dreams and the Ethereal Plane, but also very prone to leakage from the Far Realm. A peaceful race who fill much the same role in their realm as humans, this overwhelming onslaught of true horrors has served to drive many of them to abandon their homes and seek a new life on the Material Plane. Something rather difficult given that they tend to find most humanoids as being as scary and alien as those humanoids find the diaboli.
See, a diabolus looks pretty much like your stereotypical devil. From the waist up, a diabolus looks basically like a human - if you can ignore the fact their skin coloration comes in various shades of purple, from mauve and lavender to near-black violet. At the waist, however, they sport digitigrade legs ending in cloven hooves, much like a goat or a sheep, and long, whip-like tails tipped with pronounced, curving sickle-blade stingers of bone; these can inject a debilitating, but ultimately mild, toxin. Their hands lack the pinky finger of a human's hands, and their face is marred by the presence of two thumb-sized, vestigial horns rising from the top of the head or the brow, a "Roman" nose, elf-like ears that stick out at severe angles, "reptilian colored" eyes in hues such as red or yellow, and long, fork-tipped, snake-like tongues. In addition to that, diaboli are informally divided into three subspecies; one species grows hair much like any human does, whilst a second, known as the "hirsute diabolus", has more pronounced hair-growth, with coarse, goat-like fur adorning their legs; the third, known simply as "bare diaboli", sprouts absolutely no hair at all, with even the women lacking so much as a strand upon their head or anywhere else. This difference is literally only skin deep and there's no greater divisions between the subraces.
The diabolus mindset is naturally aligned towards the chaotic; their society exists in what is essentially anarchy because they believe that as no one government style is provably better than the rest, then it's best to just not have anything to do with the hassle of government whatsoever. The diabolus society, such as it is, holds together mostly through strong customs and traditions that have proven repeatedly to be helpful, and a strong sense of fair play; the guiding philosophy of the diaboli can be summed up as "do what thou wilt, but harm none", the foundational "great truth" that unites their people and which provides the roots from which all taboos, traditions, and customs ultimately grow.
One oddity from second edition that was left out of third was that, originally, diaboli were immune to magic cast by natives of the material world - but, at the same time, magic used by diaboli would have no effect on material-worlders, either.
The 3.5 stats for diaboli are as follows:
- No ability score modifiers
- Type: Outsider (Native)
- Base land speed 30 feet
- +2 racial bonus on all saving throws against spells and spell-like effects.
- +2 racial bonus on Intimidate checks made against animals and humanoids.
- -2 racial penalty on Diplomacy, Handle Animal, Perform and Sense Motive checks against Prime Material races.
- Weapon Familiarity: Tridents are a Simple weapon for diaboli and not a Martial weapon.
- Natural Attack: Tail Sting. This is a secondary natural attack (-5 to-hit penalty) that does 1d4 damage and injects poison (DC 10 + 1/2 HD + Con modifier) which Sickens the victim for 2d4 rounds as its initial damage and has no secondary damage.
- Favored Class: Sorcerer