Belisarius Cawl - Indomitus Crusade and the Ultima Founding: In fact, Cawl's work on Mars had been nothing less than an attempt to improve upon the Emperor's own works of creation.For ten standard millennia, the archmagos dominus had been working on another task set for him by the primarch Roboute Guilliman before he was mortally wounded by the Daemon Primarch Fulgrim at the Battle of Thessala in the days after the Horus Heresy: a new legion of transhuman warriors.In the time after the Terran Crusade, though the Imperium was poised on the brink of annihilation at the hands of Chaos, Cawl's task was at last completed. The Primaris Space Marines were a new generation of transhuman warriors developed across the span of ten standard millennia by Cawl on Mars. Cawl used the genetic template of the original Space Marines created by the Emperor for His Great Crusade as the starting point for the development of the new Astartes. Primaris Space Marines are bigger, more physically powerful and possess faster reaction times than their original Astartes counterparts.The Primaris Space Marines raised in the so-called Ultima Founding of 999.M41 are a new breed of hero for this, the darkest age in the Imperium of Man's history. These new warriors were the next step in the evolution of the Emperor's Angels of Death, and timely reinforcements for the Imperium's armies as their enemies closed in for the kill in the wake of Abaddon the Despoiler's 13th Black Crusade and the birth of the Great Rift dividing the Imperium in two.To aid them in battle, these gene-forged warriors were equipped with new arms and armour forged on Mars itself at Cawl's direction, such as the Mark X Power Armour worn by the various types of Primaris Space Marines, which combined the most effective elements of ancestral Horus Heresy patterns of battle-plate with more recent developments in power armour technology; the Mark II Cawl Pattern Bolt Rifle, the archetypal firearm of the Adeptus Astartes, now re-engineered, re-crafted and perfected; the Mark III Belisarius Pattern Plasma Incinerator, a new refined Plasma Gun; Redemptor Dreadnoughts, the Overlord gunship, and Repulsor grav-tanks.At the dawn of the Indomitus Crusade called by Guilliman to throw back the forces of Chaos, these phenomenal new warriors joined the resurrected lord commander of the Imperium as he fought to liberate the scattered bastions of Imperial space. Some, Guilliman forged into new Space Marine Chapters, whole brotherhoods comprised only of these new transhuman warriors. Others he has offered to the existing Space Marine Chapters. Many Chapter Masters have welcomed their Primaris brethren into their ranks, accepting the new reinforcements gladly. Others, though, view these new creations with suspicion or outright hostility, claiming that the Emperor's work should never have been meddled with by mere mortals.Though they are a step removed from their brothers, the Primaris Space Marines still bear the gene-seed of their primarchs, and some dissenting voices worry how this new type of warrior will react with the known genetic quirks and flaws of some of the more unusual Chapters, such as the Blood Angels and the Space Wolves. The Primaris Space Marines offer new hope to a besieged Imperium, but the future remains a dark and uncertain place.During the Indomitus Crusade, Cawl was given free reign by Guilliman to unleash technological innovation to help the forces of the Imperium finally throw back the tides of Chaos. Cawl had been authorised to utilise new technology and new configurations of ancient devices to refit Guilliman's flagship, the Macragge's Honour. The ancient archmagos had proven to be the Imperium's only source of technological innovation across the span of the Indomitus Crusade, creating several new vehicles and weapons to outfit the formidable legions of Primaris Space Marines and the original Chapters of the Firstborn Adeptus Astartes.During the first solar decade of the Indomitus Crusade, Cawl became increasingly detached from the wider galaxy, instead focusing on his quest to create and perfect the Primaris Space Marines of the Ultima Founding and deploy them wherever the Indomitus Crusade Fleet Primus went to reinforce existing Firstborn Space Marine Chapters or to establish new Primaris Marine-only Chapters.As part of that initiative, he sought to persuade Guilliman to allow him to utilise gene-seed from the nine forbidden genetic lines of the Traitor Legions and even the two long-lost II and XI Legions. Cawl claimed that there had been nothing wrong with these gene-lines, as their Space Marines had operated as the Emperor had intended and that adding their tactical diversity to the Imperium would greatly strengthen the new Primaris Marines. Cawl claimed that the flaw in the Traitor Legions and the Lost Legions had lain in their primarchs, not their gene-seed.But Guilliman emphatically refused, and ordered the archmagos to not progress any further with this research, even as he knew that Cawl would most likely take it upon himself to pursue such heretekal lines of inquiry on his own. Guilliman was no fool, for he knew that all magi of the Adeptus Mechanicus hungered for knowledge. When they had it, they could rarely refrain from using it. On this particular matter, he did not trust Cawl one whit.Some twelve standard years after its inception, as the Indomitus Crusade reached the conclusion of its first phase of stabilising the Imperium Sanctus at the Battle of Raukos, Cawl had already been retasked by Guilliman to pursue a new line of crucial research -- discovering how the blackstone Cadian Pylon technology developed by the Necrons millions of Terran years before might be used to seal the Great Rift.