Typhon's backstory is a little fuzzy - some sources suggest he was a Dusk Raiders Librarian, others emphasise his birth on Barbarus and that he's connected in some way to its alien warlords.


It may be a case of - when Mortarion was brought to Terra by the Emperor, several of his followers were brought along - including Typhon - who enrolled in the Dusk Raiders Librarium - then, around the same time Mortarion renamed them the Death Guard, the Librarium was closed by him and all Librarians returned to the ranks.