Darktongue

A strange language that has been encountered in a few scattered books and journals. The origin of Darktongue remains unknown; it bears the most similarities to Abyssal, though fragments of Infernal and Sylvan also appear. Even with these possible traces to a mother tongue, Darktongue is complex and distinct-- maddening difficult to learn without some sort of guide or teacher. A primarily written language, although certain writings hint at the ability to speak it as well. 
The common thread between all Darktongue writings is a focus on/interest in forbidden magics; necromancy, hemocraft, and other dark rituals have been transcribed in Darktongue by various unknown writers.