She first appears in Book II, Chapter 5, where, after tracking down the Order of Heroes, she demands they surrender, offering to spare them if they do so. Upon their refusal, she leads her forces, her sister Laevatein among them, into battle, but is pushed back. Admitting defeat, Laegjarn and Laevatein retreat. Afterward, Laevatein considers resorting to a power that could end up destroying her, but Laegjarn immediately orders her to never use it, and Laevatein relents.
Mulling over the Askrans' motives for traveling to Nifl, she realizes that they are trying to discover a way to defeat Múspell. She comes to this conclusion based on the determination she witnessed among the Askran forces, noting that they would not be so resolute in their actions if they weren't certain there was a way they could win the war. She then starts crafting a plan to attempt to cut off the Order before they can turn the tide of battle. Though she is careful in her pursuit, she realizes too late that she has fallen into a trap; knowing the danger she posed, the Order lured her into an ambush. Laegjarn orders Laevatein to flee, and is subsequently defeated and captured.
Though Laegjarn assumes she will be tortured or executed, the Order expresses the respect they have for her as they prepare to hold her captive. However, while the Order witnessed Surtr killing Gunnthrá, Laegjarn escaped.
Pursuing the order in Múspell, she's seen again at the end of Chapter 10, where she comments about the report of Hríd managing to escape once more, explaining that even wounded, Hrid is still a formidable foe as he infiltrated the kingdom and tried to kill Surtr on his own and, deeming it a dangerous prospect, decides to find him before he join forces with the Askrans. For that end, she coerces Helbindi into aiding her, pointing out that if either Surtr or Loki finds out about his survival, he will be killed or worked to death, but if he succeeds, he will live and be able to help his sister. However, Laegjarn releases him from his duties in Chapter 12, regrettably informing him that her father burned the slums he lived in and killed everyone there along with his sister, making the blackmail pointless.
Her final appearance is in Chapter 13 where she sacrifice herself for the Rite of Flames to prevent her father from killing Laevatein. After being defeated one last time by the Order of Heroes, she suffers fatal injures and succumbs to her death. Before she dies, she tells Fjorm that she wished things turned out differently between Nifl and Muspell, and makes a final request to Fjorm and the others, asking them to save her sister, Laevatein.