Lord Phaedrus was Master of the Adeptus Astra Telepathica and a member of the High Lords of Terra in M36 during the Age of Apostasy. A powerful Psyker, Phaedrus represented a threat to Goge Vandire's ascension to absolute power within the Imperium as his formidable psychic abilities allowed him to be one step ahead of whatever schemes or machinations Vandire could come up with. Eventually Vandire deployed Culexus assassins of the Officio Assassinorum to deal with Phaedrus. The assassins drained Phaedrus of his psychic powers, stopping short of killing him in order to avoid another powerful psyker simply taking his place. Robbed of his power, Phaedrus agreed to follow Goge Vandire on the condition that none would know of the loss of his psychic abilities, which led to Vandire's domination of the Adeptus Astra Telepathica.