The following contains spoilers for Avengers Assemble: Alpha #1, now on sale from Marvel Comics
Mephisto has always been one of Marvel's most nefarious villains, with his schemes within schemes always moving against the intentions of the heroes. His apparent focus on Earth-616 has been the focus of recent Avengers storylines, but it turns out there's an entirely different reality he's been after all along.
Avengers Assemble: Alpha #1 (by Jason Aaron, Bryan Hitch, Andrew Currie, Alex Sinclair, and VC's Cory Petit) reveals that Mephisto's plans have always been to create an opening to overwhelm and conquer the God Quarry instead of Earth-616.
Mephisto Has Finally Revealed His True Goal
At the heart of Jason Aaron's sprawling Avengers run that began in 2018 has been the conflict between Mephisto and Avenger-Prime. The latter -- a mysterious force for good -- has been rallying a multiversal army of Avengers, while Mephisto's manipulations across the multiverse have gotten entire realities destroyed. The devilish villain has been able to turn the entirety of creation into his battlefield, pitting an unstoppable band of villains against a disorganized heroic force. Meanwhile, his presence on the battlefield draws the attention of Avenger Prime, who goes to confront Mephisto. The two quickly trade blows, and Avenger Prime proves capable of holding his own against the evil entity.
But the problem is that there isn't just one Mephisto there, as the villain had assembled an entire army of his own variants. Dubbed the Council of Red, the Mephisto alliance is able to overwhelm the hero and then use his portal to the God Quarry. As Mephisto explains to the injured hero, he never really wanted any version of Earth. His mission has been to gain access to the God Quarry, a realm rich in power thanks to the "rotting deities" that make up the world. From this dimension, all existence across the Marvel multiverse grows. It is from here that elements like the First Firmament came to being, separating existence from the nothingness that came before it. Alongside his army of Mephisto variants, the villain seeks to claim the Avengers Tower, destroying their greatest threat while gaining access to the massive power that resides within the God Quarry, potentially making Mephisto the single most powerful force in existence.
Marvel's Earth-616 Was Never Mephisto's True Goal
It's a deft reveal, as it makes Mephisto's insistence on Earth-616's importance more of a feint than it may have appeared previously. The heroes of Earth-616 were the most resilient in the multiverse and the most capable of finding a way to hold back the armies of Mephistos. But the Earth itself was never the target of the Earth-616 Mephisto, who instead is seeking out a far more potent power within a graveyard of deceased deities. With that kind of power, Mephisto could potentially rewrite the entire multiverse in his image (similar to his role in Heroes Reborn), or even simply wipe out anything and everything he deems ill-fit to his liking.
On the one hand, this shifts importance away from the Avengers of Earth-616, as their world isn't the true target of the battle. If anything, Mephisto's targeting of the world seems to be mainly to keep these heroes off the board and distracted from the actions of the Council of Red. Meanwhile, it places a greater level of importance on the fate of Avenger Prime and his Avengers Tower, giving the combined Avengers Army a far more vital mission. The God Quarry being Mephisto's true goal is a solid swerve away from the apparent importance of Earth-616, and gives Marvel's devilish foe a more specific goal.