Following the flight of the few surviving Thousand Sons to the Planet of the Sorcerers during the epic conclusion of the Burning of Prospero at the start of the Horus Heresy, the Blades of Magnus were the first of Prospero's Sorcerers to devote themselves wholly to their Primarch's salvation. They worked in secret to break the bond between the Crimson King and the eldritch forces he had embraced. The Blades adopted the colours of Magnus' personal guard, the Rehati, but wore them in reverse -- in this way they demonstrated their intent to save Magnus from himself. For long years they toiled in secret, slaying those daemons with which Magnus had made his devil's bargains. When the Daemon Primarch learned of their works, he did not reward them, but blasted them with annihilating mental power.