Before the battle of Ragnarok, the witch Gullveig entered Valhalla under guest-laws prohibiting the spilling of blood. There she refused to teach Odin the talent of sedir - the weaving of fate and prophecy. Odin broke the sacred guest-laws and Gullveig was burnt to death three times, regenerating each time. A spear to her heart killed her.
Then, she burned and Loki and gods did nothing, she gave one final lesson in sedir...