The Armour of Fate is a specially-crafted suit of Artificer Armour created specifically for the resurrected Primarch Roboute Guilliman. Crafted by the armourers of the Adeptus Mechanicus at the direction of Archmagos Dominus Belisarius Cawl over the course of almost 10,000 standard years, its inner workings enhanced with advanced life-sustaining technologies, this glorious suit of highly advanced and unique Artificer Armour fits Guilliman perfectly, and protects him from even the most dolorous of blows.
The suit, along with the rest of the Primarch's panopoly, had been kept in safekeeping by Cawl on Guilliman's orders since the period immediately after the Horus Heresy in the early 31st Millennium. During the Ultramar Campaign in 999.M41, Cawl and the other members of the Celestinian Crusade travelled to Macragge and convinced the Ultramarines Chapter Master Marneus Calgar to let them go to the Temple of Correction and seek to revive Guilliman, who had been in stasis there for more than ten standard millennia, since he had been mortally wounded by his brother, the Daemon Primarch Fulgrim, at the Battle of Thessala. With the assistance of the Ultramarines' Chief Librarian Varo Tigurius, Cawl worked with his ally Yvraine, the leader of the Eldar faction known as the Ynnari, to combine the technological capabilities of the Armour of Fate with the power of Yvraine's recently awakened god, Ynnead, the Eldar God of the Dead, to heal the Primarch's wounds and restore him to life.
- Gathering Storm - Part Three - Rise of the Primarch (7th Edition), pp. 4-93, 128-129