Epistolary: The highest ranking and most powerful of the Space Marine psykers, with the exception of the Chief Librarian. They reside in the Chapter's Librarius and only take to the field on the direst of occasions, generally when facing a large foe or Greater Daemon.
Source: Codex: Space Marines, 3rd Edition by various, Codex: Ultramarines, 2nd Edition by various
Submitter: IBBoard
Hive World Terra