Bjorn: Lone Wolf is the thirteenth short story published in the Horus Heresy that was not originally part of an anthology novel. It was originally published online in December 2013 as part of the Black Library Advent Calendar, on the Black Library's website. It is also now included in Legacies of Betrayal anthology novel. Covers for both the original and updated artwork is shown.
As daemons swarm across the fields of Velbayne, bringing madness and Chaos to all that they touch, Leman Russ and the Rout stand arrayed against them. Packs fight back to back, brothers protecting one another except for one. The Lone Wolf, the warrior without a Pack, stands alone. And somewhere on the battlefield is a foe against which he will have vengeance.
- Bjorn: Lone Wolf (Short Story) by Graham McNeill