Magnir is one of the Asgardian Enchanters, a group of powerful magic users who call each other "brothers". Uncertain if they are actually related or members of a brotherhood. He has superhuman strength, estimated to be able to lift between 20 and 30 tons. As such he is slightly less strong than the average Asgardian. He wields a sword in combat.
Magnir was able to negate Odin's enchantment over Mjolnir and briefly used the hammer in battle. He was defeated by Balder in combat and exiled to Limbo. He was later released by one of his brothers but defeated again by the Scarlet Witch. He was returned to Limbo and presumably still awaits release.
Magnir was created by Stan Lee
and Jack Kirby
in 1967 and first appeared in Thor