Thor, Vol. 1

Igron tells Thor how he came across a diminutive Mangog in the dungeon. Igron then stole a portion of each Asgardians life force to bring Mangog back to power, which explained their lethargic state. After Odin regained his memory and left Earth for Asgard, he disappeared and never arrived. Igron then cast a spell to make Mangog look like Odin, and thus their plan was born. The guards then attack Thor and while he is distracted, Mangog strikes him down. Elsewhere, the warriors rally the people to their cause, but when they arrive at the gates, they see Thor shackled up like a scarecrow. As they strike, Mangog (back in disguise), transforms them all to animals. He finally snaps and kills Igron as well, which ends his disguise and everyone knows it's really Mangog and not Odin. Thor manages to break himself free, and races Mangog to the Odinsword. As Mangog beats Thor there, he vanishes away. Without the worship of the Asgardians, he no longer had any power to keep himself together.