The Triumvirate of the Primarch was the name given by observers to the odd tripartite alliance between a Primarch, a Grey Knight and a Fallen Angel during the Terran Crusade ... and perhaps beyond. A strange fate binds Roboute Guilliman of the Ultramarines, Grand Master Aldrik Voldus of the 3rd Brotherhood and the enigmatic Fallen Angel Cypher together. As one, they walk a path of providence, though whether it ends in damnation or deliverance none can say. Upon the field of battle this triumvirate of warriors is an unstoppable force, bolstering the might and morale of those they lead while sundering the enemy battle line with their sheer, unstoppable strength. Cypher's twin pistols -- one an archaic Bolt Pistol, the other an ancient Plasma Pistol -- roar. Voldus' psychic powers lash out to engulf the enemy in cleansing ﬂames or shield his allies from harm. At the very heart of the battle, Guilliman strides like a reborn god, bellowing rallying cries to inspire his warriors even as he hacks, crushes and blasts down rank after rank of the foe.
- Gathering Storm - Part Three - Rise of the Primarch (7th Edition), pg. 130