Marvel's Avengers may be Earth's Mightiest Heroes, but that doesn't mean they don't need a power-up now and then. One of their most impressive power-ups came courtesy of Matt Fraction and Stuart Immonen's Fear Itself, the Red Skull's daughter Sin uncovered Odin's dark secret. This resulted in some of Marvel's most powerful characters, the Worthy, being imbued with the dark power of Asgardian weapons at the behest of Odin's evil brother Cul Borson.
The Avengers were greatly outmatched by the Worthy, which grew to infect members like the Hulk and the Thing, who became Nul: Breaker of Worlds and Angrir: Breaker of Souls, respectively. Reacting drastically, Odin prepared to raise Midgard to stop Cul and his Dark Gods, as well as prevent his son Thor from fulfilling a prophecy that would see him kill Cul at the cost of his own life. However, Tony Stark decided to put his mind to work with other ideas and requested an audience with the All-Father himself.
Ever the futurist, Tony recognized that to beat a group of Asgardian empowered foes he would need to create a team of Asgardian empowered Avengers. Out of respect for Tony based on his alliance with his son Thor, Odin granted Tony's request. The events that followed saw the Avengers decked out in Uru armor and weapons in their final battle to defend the Earth. The heroes were granted Hawkeye's Asgardian bow, Iron Fist's Asgardian mace, Spider-Man's Asgardian stingers, Wolverine's Asgardian claws, the Asgardian Savage Sword of She-Hulk, Doctor Strange's Asgardian staff, Ms. Marvel's Asgardian ax, Black Widow's Asgardian swords and the Iron Destroyer Armor. Even Thor takes up a new weapon, the Odinsword Ragnarok, in the final battle against Cul.
However, in the time that Tony was gone creating these weapons, Captain America's shield had been broken. Not knowing this, Tony returns without a gift for Cap, who seems more than happy donning the weapons of civilians in his holding of the line. Eventually, an explosion sees Cap separated from his guns and weaponless, but it's not long before he finds a weapon left just for him, leading to a moment that would famously be echoed in Avengers: Endgame
While Captain America wasn't the first Avenger to lift it and had even lifted it before, the sight of Captain America holding Mjolnir completes the idea of an Asgardian powered Avengers team. This moment completely shifts the tide of the battle as well, where previously the world was in bad shape and Odin was poised to essentially destroy it to win, the arrival of the Mighty and a Mjolnir-wielding Captain America return hope to Earth and strikes fear into their foes.
Thor and Black Widow put their new swords to work quickly on their enemies, while Hawkeye's new bow grants him the ability to shoot at a variety of angles. We also see Iron Fist and Doctor Strange combine their innate mystical powers with their new Asgardian weapons, while Cap masterfully wields Mjolnir and She-Hulk slashes and smashes her way through hordes of villains with the Savage Sword.
Eventually, Odin arrives to join the battle, but not before Thor fulfills the prophecy by slaying the Serpent Cul and losing his life in the process. The Worthy are relieved of their weapons, while all members of the Mighty except for She-Hulk relinquish theirs as well. She-Hulk would go on to wield Asgardian Savage Sword in both Matt Fraction and Terry Dodson's Defenders series, as well as Jeff Parker, Carlo Pagulayan, and Wellington Alves' Red She-Hulk series.
It's rare that the Avengers have to look outside of their extended group of heroes for help when it comes to world-ending events, but this one led to a new look for Earth's Mightiest Heroes. While they may not have had much time with their new weapons, this crossover's finale gave us a glimpse of just what it might look like if the Avengers became Asgardian Gods.