During the Heresy he joined Malcador's Knights-Errant at the order of his Primarch Leman Russ. He was one of the key Knights-Errant personnel during their attempt to infiltrate and mark Vengeful Spirit in preparation for Russ to slay the treacherous Warmaster. The team was discovered, but Tyrfingr managed rip out the throat of Tormageddon before escaping aboard his spacecraft Tarnhelm with several other Knights-Errant.
Though still an agent of Malcador, Bror rejoined his legion during the Battle of Trisolian to aid Russ against the traitors. During the battle he led a boarding party with members of his former pack, but became lost in the ever-shifting corrupted form of the Vengeful Spirit. Bror and his pack were eventually confronted by Abaddon and his Justaerin and subsequently massacred.
- 1: Vengeful Spirit (Novel),[Needs Citation]
- 2: Wolfsbane (Novel) Chapters 15–27
- 3: The Horus Heresy: Legions