Magnus has blue eyes with lines in the corners of them. His hair is blonde and he sports a beard. In the miniature, he is described as looking graver than his son and obviously a bit older. His laugh is identical to Nikolai's.
In Rule of Wolves, his beard is streaked with grey and his build is skinner due to being held prisoner.
Tamar, Tolya, and the triumvirate receive news that Fjerda is preparing to march on Ravka under the Lantsov banner. Their rulers have declared for Vadik Demidov, who says he is a Lantsov cousin and rightful heir to Ravka's throne. This claim is supposedly supported by Magnus who claims to be Nikolai's biological father as he had an affair with Queen Tatiana. This is further proved by Magnus' possession of the Queen's letters to him. This plan to march on Ravka is not known by Fjerdan public officials yet.
Nina finds Magnus in a cell next to Jarl Brum's office. It is revealed that Magnus refused to speak out against his son and lover and as a result was kidnapped from his home and taken prisoner as insurance for Vadik Demidov and Queen Tatiana's love letters. He begs Nina to help him escape, trying to tell her of Fjerda's plans to bomb Os Alta, but she cuts him off and promises to come back for him. He manages to escape the cell using a bone shard he pulled from Nina's sleeve. He makes it to the lower town in Os Alta where the warning bells ring right as the attacks begin.
Magnus travels to Lazlayon where he asks to see Nikolai. Flanked by Zoya and some guards, Nikolai meets Magnus at the gates where he is given a wrapped miniature of Queen Tatiana. Nikolai requests Zoya and the guards to leave them and Magnus explains that he had shown up to try to warn him of the bomb plans and see his son once before he starts a new life in Novyi Zem. Magnus also asks that Nikolai look out for Linnea, who can not directly inherit any money from Magnus due to Fjerdan law.
- Magnus is a late Latin name meaning "great".
- Fjerda's codename for Magnus as prisoner is Rëvfeder which translates to Foxfather