God Tempest of Remnant

According to the records of Omnipotence City's Halls of All-Knowing, the phenomenon known as the God Tempest, or the Mother of Thunder, was a cosmic thunderstorm that existed since the dawn of time and grew gradually in size each eon that passed. The worst of its wrath was reserved for those who truly deserved it, which made people believe it had a mind of its own.

On its path of destruction, the God Tempest eventually reached Asgard. The All-Father Odin confronted the storm and fended it off for days with the power of the Odin-Force. Once the storm grew tired and weak, Odin struck it with a nugget of Uru, which had been gifted to him by the Dwarves of Nidavellir. Through dark and primal magic, the storm became entrapped inside the Uru.

However, the storm still raged inside the hammer, and Odin failed to contain it, forcing him to enchant it to prevent anybody else from lifting it. Mjolnir was left to sit in the weapons hall of Asgard for ages. According to the Lord Librarian, the God Tempest eventually died, and only its power remained within Mjolnir. But that was just a misconception.

The hammer would become the weapon of Odin's son Thor, who proved himself worthy to bypass the hammer's enchantment. Many ages later, the hammer appeared to have regained its sentience. After Thor lost his ability to wield it, the hammer also rejected Odin's grasp, and this was when the hammer decided to travel the multiverse in search of a worthy wielder. It has traveled for over a thousand years until it finally detects one that is worthy of its power, one that would not abuse it and would use it to its very limit to protect the innocent and use its wrath to bring forth judgment to those who truly deserve it.