Asger was already a Wolf Lord when the Ork forces of The Beast invaded the Imperium. He took part in his Chapter's battle against the Orks, when they invaded an Imperium System near the Eye of Terror and he later successfully led his Great Company in defending the Industrial Moon Fabrikk, when it was invaded. Afterwards, he was commanded by his Great Wolf to travel to Terra, after the Space Wolves received word that their aid was requested[1a] for a strikeforce; to attack the world Ullanor, which was discovered to be the origin point of The Beast's invasion force.[1b]
He later appeared before Lord Commander Koorland as part of his Chapter's taskforce on Terra. He reluctantly tolerated the presence of Dark Angels[1c] and took part in the invasion of The Beast's homeworld of Ullanor. Warfist later became one of the first members of the Deathwatch and took part in the destruction of the Attack Moon over Terra.
Shortly before the second invasion of Ullanor to try and once again slay the Beast, Lord Commander Koorland made Asger Warfist the first Chapter Master of the Deathwatch. Warfist fought alongside Koorland as the Lord Commander died against the second "Beast"-class Warboss that revealed himself.
During the third Imperial offensive on Ullanor, Asger Warfist commanded one of the five Imperial attack groups.
- 1: The Hunt for Vulkan (Novel)
- 2: The Beast Must Die (Novel) Chapter 3
- 3: Watchers in Death (Novel) Chapter 3
- 4: The Last Son of Dorn (Novel) Chapters 17–18
- 5: Shadow of Ullanor (Novel) Chapter 7