Amon once served as a tutor to the Primarch Magnus the Red, before the arrival of the Thousand Sons Space Marine Legion on the world of Prospero during the Great Crusade in the late 30th Millennium. He eventually went on to become one of the XVth Legion's first Prosperine Astartes at the direct invitation of Magnus. Amon rose through the ranks to become the Captain of the 9th Fellowship. As a potent psyker, he became the founder of the XVth Legion's Corvidae Cult and its first Magister Templi. He also served as Equerry to Magnus, responsible for the Primarch's security and for officiating certain sorcerous rituals, amongst other duties. Amon would not only survive the battles of the Great Crusade, but the Razing of Prospero by the Space Wolves Legion during the early years of the Horus Her