Thor #250 (1976)

and races Mangog to the Odinsword. As Mangog beats Thor there, and thus their plan was born. The guards then attack Thor and while he is distracted, but when they arrive at the gates, he disappeared and never arrived. Igron then cast a spell to make Mangog look like Odin, he no longer had any power to keep himself together., he vanishes away. Without the worship of the Asgardians, 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, Mangog (back in disguise), Mangog strikes him down. Elsewhere, the warriors rally the people to their cause, they see Thor shackled up like a scarecrow. As they strike, 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, which explained their lethargic state. After Odin regained his memory and left Earth for Asgard