During the conflict with Thanos, Thor ventured to Nidavellir with Rocket Raccoon and adolescent Groot to forge Thor's new weapon. Upon arriving, the typically lively forges of Nidavellir were cold and barren, littered with broken parts. The initially scared Dwarf King Eitri found himself reunited with his old friend, and explained that the dwarves had been rendered all but extinct and his hands had been fused off with metal as a result of Thanos's request of the forgery of the Infinity Gauntlet.
With Thor and Rocket Raccoon's help, Eitri reignited the dying star and re-lit the forge, melting down ingots of Uru and pouring it into a mould. He then shattered the mould, revealing the axe's blade and weight, but misplaced the handle for the weapon. Seeing that Thor was close to death after taking the burnt of the dying star's power, Groot decided they could not wait for Eitri to find or create a metal handle; he grasped the red hot pieces of metal with one of his arms (causing Groot considerable pain) and then cut the arm off to serve as the handle, truly finishing Stormbreaker. The weapon then revived the smoking husk of Thor, who used its power of the Bifrost to go forth to Wakanda and assist his fellow Avengers.
Stormbreaker was used in the Battle of Wakanda to great effect, augmenting Thor's own lightning massively. It was, notably, the only weapon that caused any noticeable harm to Thanos during the entire conflict: Thor impaled Thanos using it just after Thanos completed the Infinity Gauntlet; however, he intentionally aimed for the chest instead so he can gloat to Thanos, resulting in Thanos only being badly injured rather than instant killed, which proved to be a fatal mistake that Thor would soon regret deeply, as the blow could not stop Thanos from activating the Infinity Gauntlet, wipe out half the universe and escape, with the wound closing soon after upon Thanos activating the Gauntlet.
CapabilitiesUru, the weapon is nigh-indestructible and able to withstand energy blasts created by the Infinity Stones. It is also able to channel dimensional energy and act as a Bifrost Bridge, which is shown when Thor teleports himself, Rocket Raccoon and Groot to Wakanda instantly.
Like Mjølnir before it, Stormbreaker will return to Thor's hand when summoned, and strikes his opponents with massive force. It glows with an otherworldly blue flame that crackles with electricity, and seems to have the ability to home in on a target if Thor wills it. In addition, the weapon allows the user to fly seamlessly while using it, unlike Mjølnir, which required the user to spin it at great speed to lift them off the ground.
Due to its increased size and mass, having both the blade of an axe and the head of a hammer in its construction, as well as sporting an elongated handle enabling the weapon to be wielded two-handed, it is a notably more potent melee weapon than Mjølnir that came before it. Eitri even went as far as to say Stormbreaker is the strongest weaponry in Asgard's history. As a weapon designed to kill Thanos, it is one of the extremely few able to harm and injure him, with Thor thus managing to cause Thanos considerable pain and injury when he twisted the axe deeper into his chest. It is so powerful that it was able to deflect a blast from the completed Infinity Gauntlet.
- In the comics, the Stormbreaker was created by Odin as a weapon for Beta Ray Bill, after he returned Mjølnir to Thor.