Milestone: Killed by Odin Borson
Surtur is the fearsome fire demon and ruler of Muspelheim, the original forger and wielder of the blade that bears his name, the Sword of Surtur. Long before the events of the quest, he was drawn into the war between the Dark Elves and the Frost Giants, siding with the Dark Elves for their survival, until Odin entered the conflict and struck him down to keep the fire demon from turning his ambition on all the Nine Realms.
He appears now only in the reconstructed memory of that ancient battle. Recalling the many tales of valor they memorized as children, Thor and Loki piece together the story of Odin's victory over the fire giant in a Jotunheim valley, recognizing the terrain and retracing how the Allfather tired Surtur until the exhausted demon needed both hands to lift his blade and left his chest exposed. The Allfather dealing a devastating blow.