The following contains major spoilers for Avengers Forever #15, on sale now from Marvel Comics.
For years, Earth's Mightiest Heroes have pushed back against the threat of Mephisto and his multitude of schemes. Along the way, they have traversed time, space, and the depths of the Marvel Multiverse. Now the culmination of their battles has brought the heroes to the God Quarry for one final confrontation. Unfortunately, this isn't just set to be the Avengers' final fight with the demon they know best, but also the last of any fight across any reality, and all because they unwittingly helped Mephisto break the multiverse.
Avengers Forever #15 (by Jason Aaron, Aaron Kuder, Mark Farmer, Frank Martin, and VC's Cory Petit) finds the last remaining heroes facing off against what continues to seem like an endless wave of enemies. In a stunning display of power, Thor and his mother Firehair, better known as the Phoenix, unleash a massive strike that tears the ground asunder. Unfortunately, it is just this sort of destructive act that Mephisto has been waiting for, as everything he has been fighting toward is sealed beneath the God Quarry, as it is revealed to be the multiversal damn holding back a tide of entropy.
Mephisto May Have Just Torn the Marvel Multiverse Apart
As horrifying as it is to see a wave of manifest entropy, or as Old Man Phoenix describes it the "liquefied leavings of an ancient multiverse," the true shock comes from the realization that the Avengers never really understood what they were fighting for. Of course, Mephisto has given them plenty of reasons to believe that he had vastly different goals in mind at every single step along the way. Though Mephisto has always been a formidable threat, it wasn't until the arrival of his Squadron Supreme of America that it became clear he had grander plans in motion than ever before.
With Phil Coulson's help, Mephisto reshaped reality into a world where the Avengers never existed, and where the Squadron Supreme lorded over the rest of the world. Worse still, when reality was set right by Earth's Mightiest Heroes, Mephisto called upon his Council of Red to revel in the success of what was presumably a test run for a multiversal takeover. Coupled with his latest campaign and continued interest in destroying the legacy of Spider-Man, it looked like he was determined to remake the entire multiverse in his image. However, breaking the God Quarry made it painfully obvious that ruling all reality was never what he had in mind.
The Avengers Need More Help to Defeat Mephisto
Beyond reframing everything Mephisto has done over the past few years, this new development completely changes what it is that Avenger Prime and his fellow heroes have to worry about, not to mention what they can do about it. Fighting an army of Mephistos or Doctor Dooms is one thing, but finding a way to hold back the physical embodiment of entropy itself is not a problem they can simply beat into submission. If anything, the heroes will have to hope that others will join the fight to save the multiverse and they might not have to look far to find them.
Considering the way that Mephisto has drastically raised the stakes at hand, it isn't out of the question for one or several of the other villains the Avengers have fought against to make an abrupt turn. After all, if there is no multiverse, there is nothing for any of them to claim dominion over or unleash their wrath upon. This might be acceptable for complete nihilists such as Kid Thanos, but that is hardly going to be the case where the rest are concerned, least of all an entire legion of Dooms.