Abaddon's mastery over the Black Legion was solidified during the 1st Black Crusade after his quest to slay the clone of Horus created by Fabius Bile, the former Chief Apothecary of the Emperor's Children Legion during the Legion Wars. His inhuman power, bestowed by the Chaos Gods, and his acts of suicidal bravery horrified his enemies. His leadership, amplified by the power of the Daemonsword Drach'nyen he had claimed within the Eye of Terror, reinstated the Black Legion's standing as first among the Traitor Legions. He claimed the title of master of the Black Legion, earning the respect of his now black-armoured Heretic Astartes.