The Odinforce was a powerful magic used by Odin.
This section needs a rewrite
After the death of Sif at the hands of a Frost Goliath, Loki visited Odin who informed him that he would use the Odinforce to revive Sif. Loki told him that Thor would defy him and wage war against the Jotuns until Ragnarök. Odin stated that his intention in reviving Sif was to prevent Thor from starting another war with the Frost Giants. Loki expressed belief that this plan would work and that Thor would defend Asgard in Odin's stead while he recovered in the Odinsleep. Odin used the Odinforce to revive Sif, but stated that she would not wake for several days. Drained of an immense amount of power, Odin entered the Odinsleep.