WARNING: This article contains spoilers for Uncanny X-Men #8 by Matthew Rosenberg, Kelly Thompson, Ed Brisson, R.B. Silva, Adriano di Benedetto, Rachelle Rosenberg and Joe Caramagna, on sale now.

In the recent Infinity Wars crossover, several pairs of Marvel's biggest heroes merged to create Infinity Warps that mashed up aspects of both characters. While the X-Men didn't really have a huge role in that storyline, Marvel's two most powerful mutants just merged to form one of the strongest villains the X-Men have ever faced in Uncanny X-Men.

Throughout the ongoing "X-Men Disassembled" storyline, X-Man, an alternate reality version of Cable from the Age of Apocalypse, has been using his unlimited mutant abilities to reshape the world in his image. While Nate Grey's actions caused some real-world controversy, they also put him at odds with the X-Men and Legion, Professor Xavier's erstwhile son David Haller.

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Although he's always struggled with mental instability, the reality-warping Legion is one of the only X-Men who stands close to Nate Grey's unimaginable power level. Since Legion inadvertently created the Age of Apocalypse timeline, he also feels at least somewhat responsible for Nate and seemingly teleported him into the Age of Apocalypse a few issues ago.

As Uncanny X-Men #8 reveals, Legion actually trapped Nate and a group of young X-Men in a projection of the Age of Apocalypse that was entirely in his mind. While that kept X-Man at bay for a few minutes, Nate turned the tables on Legion by taking over his mind and body in this issue.

Unfortunately for the X-Men, this X-Man/Legion hybrid could be one of the strongest beings in the history of the Marvel Universe, and he seems ready to show the X-Men the full wrath of his vast abilities.

In "X-Men Disassembled" alone, Nate Grey was explicitly named Marvel's strongest mutant, simultaneously reached every mind in the world at once, put the powerful villain Apocalypse in chains and effortlessly erased landmarks of religious significance from around the world.

On his own, Legion is so powerful that he accidentally rewrote all of reality on multiple occasions. With the ability to spontaneously generate new abilities and hundreds of sub-personas with their own abilities, David has a strong claim to being Marvel's second-strongest mutant.

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Since these two occasional X-Men are so powerful, villains have unsuccessfully tried to take over the minds and bodies of these two mutants in the past. In several of his adventures, Legion has wrestled with his own villainous personas and the Shadow King for control of his body and his powers, both in comics and on the TV show Legion. Likewise, everyone from Apocalypse to Mysterio, the Spider-Man villain, has tried to possess or manipulate Nate and use his powers for their purposes, especially during X-Man's solo series in the '90s

While an angry Nate-possessed Legion seems like a worst case scenario for the X-Men, the precise nature of X-Man and Legion's current status isn't totally clear.

When X-Man apparently kicked Legion's mind out of his body, Nate spontaneously gave his new body his signature "X" tattoo and a white streak in his dark hair. While Legion's body is clearly a new vessel for Nate's consciousness, it's not clear if Nate can access Legion's vast array of powers in addition to his own considerable telepathic powers. Likewise, it's not clear what happened to X-Man's body, which is standing vacant on the other side of the battlefield.

Legion has rarely used the full extent of his powers, and he's almost always been more misguided than truly villainous. If X-Man can access all of Legion's powers, he could theoretically be as strong as cosmic heavy hitters like the Phoenix Force or Galactus.

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With a clear vision and a willingness to do anything to build his utopia, the X-Man-possessed Legion could pose an existential threat to the Marvel Universe. This X-Man/Legion hybrid will almost certainly play a pivotal role in setting up "Age of X-Man," an upcoming crossover that will apparently see the X-Men operating in another reality.

After X-Man/Legion hybrid unleashes his wrath and helps bring "X-Men Disassembled" to an end over the next few weeks of Uncanny X-Men, "Age of X-Man" kicks off in Age of X-Man: Alpha on Jan. 30, 2019.