The Asgardian Armor is the protective clothing which would be worn by the Asgardians as they entered conflicts. It can be summoned by magic or magical objects (such as Mjølnir) regardless of what the individual was wearing before and has the capability to withstand numerous attacks.
The Asgardian Armor was presumably developed during the beginnings of Asgardian civilization and has since been used extensively in cases of armed conflict, such as during the War with the Dark Elves. It was predominantly used by Asgardians in positions prone to conflict, such as kings and members of the royal family (Bor, Odin, Loki, and Thor), guards of the Bifrost Bridge (Heimdall and Skurge), the Warriors Three, and the Einherjar.
Thor donned the armor during an attack on Jotunheim, where he recklessly reignited a conflict between the realm and Asgard. As a result of his arrogance, Thor was stripped of his armor and Mjølnir by Odin and banished to Earth. The armor's absence rendered him defenseless to the point that he was unable to properly fight during the Battle of Puente Antiguo, leading him to lay down his life to the Destroyer in order to save the people of Puente Antiguo. Despite being mortally wounded, Thor's act of self-sacrifice allowed him to reclaim Mjølnir which automatically summoned the Asgardian Armor, restoring Thor to full health.
Two years after the Battle of Sokovia, Thor traveled to Norway with Loki to locate Odin, where he and Loki used their powers to summon their respective armors during a fight against Hela. After crash-landing on the planet Sakaar in the resulting altercation, Thor abandoned the Asgardian armor for newer gladiator armor after being forced into fighting the Hulk. However, Thor once again regained his traditional armor during the Infinity War after crafting Stormbreaker, the powerful successor to Mjølnir.
Shortly after his failure to stop Thanos and the resulting Snap, Thor seemingly abandoned his armor for good, having fallen into a depression and unwillingness to fight. After the Time Heist, however, Thanos's return prompted Thor to return to fight in the Battle of Earth, where he dual-wielded Mjølnir and Stormbreaker, restoring his armor.
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