Demonic

The common tongue of the Abyss and its denizens, Demonic is one of the Six Eternal Languages and the ancestor of Orcish, along with innumerable monster languages (Gnoll, Serpentongue, Arachni, etc.). Following its chaotic and evil heritage, the language is considered the harshest and most cacophonous of all languages--many linguists would describe it as a loosely organized system of barking, howling, hissing, and screeching, which seems only capable of expressing hateful rage and inspiring terror. It does, however, have syntax and grammar, though it is so constructed as to allow speakers to easily deceive their interlocutors. Demonic is therefore nearly impossible for non-native speakers to learn.
Demonic uses the Abyssal Script, but exact translations into any other language are almost always elusive or entirely misleading.