Angra Mainyu was a Baali High Priest who authored several blasphemous texts.
Little to nothings is known about Angra Mainyu's identity, but judging from his knowledge of symbology and religion, he was probably an early member of the Celestial or Enigma sect within the bloodline. Baali revere Angra Mainyu as the first high priest of Ba'al the Destroyer and his texts are highly valuable for them. His activity can be traced the medieval period, as he exhibited knowledge of the existence and doctrine of both Islam and Christianity, something impossible if he had been destroyed before 622 CE.
Angra Mainyu's two known texts are Distrustful Dreams, which contain numerological interpretations of the destiny of the Baali bloodline combined with references to mortal faiths and their faults. In it, he also claims that Caine had five childer, contrasting the tale of most Noddistic versions. The second text, Dreams of Angra Mainyu, is more prophetic and contains the most debased rites of the Baali, as well as a promise of infernal hordes devouring existence.
Angra Mainyu is an older Avestan term for the more modern Ahriman, the Zoroastrian adversary to Ohrmazd. Ahriman is in turn often used in reference to the Abyss utilized via Obtenebration, leaving the speculation that Angra Mainyu had ties to the early Lasombra Clan or was an Apostate of that line.