Emil Krassus was a Colonel in the 473rd Cadian Rifles Imperial Guard Regiment, who commanded its 7th Company, when it was called to defend Kast Thravius on Cadia; after it was invaded by the forces of Nurgle. Prior to Kast Thravius' invasion, the Plague of Unbelief had spread like wildfire throughout Cadia's Sector and had turned the critical stronghold into a necropolis, when the forces of Nurgle attacked. The Cadian Guard sent its forces to reinforce, Kast Thravius and they fought for weeks to prevent it from falling into the invaders' hands, but they soon only held its center; as the Death Guard and the Traitor Guard and Plague Zombies they commanded, attacked them relentlessly. As the battle dragged on, Krassus's 7th Company defended the lynchpin section of Kast Thravius still held by Cadia, when it came under attack by the forces of the Herald of Nurgle Typhus; who sought to weaken the Cadian Guard's hold on Kast Thravius and finally allow the forces of Nurgle to claim it.
In brutal fighting that followed between the two sides, Krassus was targeted by Typhus, who mercilessly cut down any of the Guardsmen who got in his way. When they finally clashed Typhus attacked with his Manreaper and the Colonel had to use all of his skill with his power sword, just to parry the Herald's attacks. As the two commanders dueled, Krassus's Command Squad came under attack by Typhus's forces and was soon destroyed, leaving the Colonel surrounded on all sides. Despite his disastrous predicament, Krassus fought on and killed several of his attackers, all the while parrying Typhus's onslaught, with such skill it seemed like the light of the Astronomicon itself, radiated from his being. However, as Krassus elatedly met Typhus's mettle, the weary Cadian officer paused for one brief second in his defense - but it was all that Typhus needed to suddenly summon forth a large number of Nurglings. Before the surprised Colonel could recover, the Nurglings bore him to the ground through sheer weight of numbers and killed him. Though what remained of the 7th Company was bereft of Krassus's leadership, they doggedly fought on and managed to defeat Typhus's forces. Such was the ferocity of their attack, that even the Herald of Nurgle himself was forced to Teleport away to safety, before he was killed.