Warning: SPOILERS for Avengers Forever #13Marvel's Thor is best known for his strength, his Asgardian heritage, and his mighty hammer Mjolnir - but the increasing importance of the Multiverse means his legendary weapon is now one of untold billions. The company's push toward the multiverse as a central conceit has resulted in characters meeting themselves, fighting themselves, and destroying entire universes in major crossover events. But Avengers Forever #13 destroys not a character or a world, but a weapon - by introducing an infinite number of Mjolnirs in a massive battle.
In the Marvel Multiverse, the reality of Earth-616 is one of many, and while some universes are vastly different from their neighbors, others are exactly alike save for minute changes. Most universes have variant characters of popular superheroes, albeit with slightly different powers; Tony Stark is the Ant-Man in one universe, and Captain America is the President of the United States in another. Avengers from every universe come together in the multiversal fight against an infinite number of Mephistos: their goal is the power that lies underneath an Avengers Tower constructed in the space between universes.
In Avengers Forever #13, written by Jason Aaron, Aaron Kuder, Mark Farmer & Frank Martin, the battle for the God Quarry rages as an army of Captain Americas and Captain Marvels fight Mephisto's ground forces. Sensing the Avengers' army is about to be overrun, the granddaughters of old King Thor call upon a nigh-infinite amount of hammers, each from a different Thor. The Mjolnirs slam into the ground, the airstrike all but obliterating the Mephistos and clearing the battlefield of enemies - for now.
An Infinite Number of Hammers Makes Thor's Mjolnir Less Special
Unfortunately, this barrage of an infinite number of Mjolnirs ruins what made Thor's hammer special. If one isn't worthy of wielding the 616 hammer, what's to stop them from simply walking through the battlefield, trying to lift hammer after hammer until they succeed? Perhaps some Mjolnirs have a similar enchantment, but perhaps some do not; regardless, this makes Thor's hammer (a weapon given to him by his father) one of an infinite number. The Multiverse, in this case, does a massive disservice to the classic Marvel characters who inhabit it.
The same principle goes for Mephisto: once a feared adversary, he is simply one Devil among many in this story. Writer Jason Aaron's Avengers Multiverse-spanning story is finally reaching a conclusion after five years, but these Multiverse-based quandaries continue to divert attention from an otherwise grandiose story. Thor's hammer Mjolnir remains special, but it is no longer unique.