Andiron was the son of Alderman and the brother of Hearthstone. He was killed by a Brunnmigi spirit.
Magnus Chase and the Gods of Asgard
The Sword of Summer
Magnus is told by Sam of his death after she learned of it from Hearthstone.
The Hammer of Thor
Magnus is told of Andiron's death.
The Ship of the Dead
Andiron's spirit appears and pleads with Alderman, who was in the form of a dragon. Alderman dismisses him, thinking him to be an illusion by Hearth.