In his haste to return Thor to Asgard, Odin takes instead Beta-Ray Bill, now posessing all the power of Thor due to his posession of Mjolnir. But armed even with the hammer, Bill is no match for Odin. As the Lord of Asgard returns his true son from Midgard, the two calmly hear Bill's tale.Struck by his need of a weapon as mighty as Mjolnir, the fact that he claims it as his due to his victory over Thor, and the simple fact that he is able to wield the weapon Odin declares that he and Thor shall enter single combat to determine who shall rightly possess it. And that the loser of the battle shall forfeit their life.
