The Unworthy Thor (comics)

Unfit to lift his hammer, with another now wielding the power of Thor, the Odinson's desperate quest to regain his worthiness takes him out into the cosmos - where he's learned of the existence of a mysterious other Mjolnir! This weapon of ultimate power, a relic from a dead universe, is the key to the Odinson's redemption - but some of the greatest villains of the Marvel Universe are anxious to get their hands on it as well. And when the Realm of Old Asgard vanishes, the Odinson's hopes might go with it - unless good tidings from Beta Ray Bill offer fresh hope! Can the Odinson reclaim his honor, or will the power of thunder be wielded for evil? Let the battle for the hammer commence!

Collecting The Unworthy Thor #1-5.