The Marvel Universe is full of impossibly powerful beings, but the X-Men's corner of the Marvel Universe includes some of the most impressive characters in the Marvel Universe. Marvel's Omega-Level mutants are all powerhouses in their own right. However, all of Marvel's Omega-Level mutants aren't quite on the same level. While characters like Storm and Magneto have a near-total mastery over the primal elements, two Omega-Level mutants, Legion and Nate Grey, are strong enough to shake the foundations of reality itself.
Now, we're taking a closer look at the ultra-powerful son of Professor X and the Age of Apocalypse son of Cyclops and Phoenix to see which mutant is truly more powerful and whether the right mutant won when they actually fought.
HOW STRONG IS LEGION?
The son of Charles Xavier and Gabrielle Haller, David Haller, or Legion, first appeared in 1985's New Mutants #26 by Chris Claremont and Bill Sienkiewicz, completely out of control of his own powers, which soon began absorbing the consciousnesses of those around him. An Omega-Level psychic in his own right, David is also able to spontaneously evolve new mutations and powers as necessary. Unfortunately, David's own mind infamously unstable, spontaneously generating dozens if not hundreds of personalities with their own mutant abilities, frequently with violent and menacing overtones.
In the ongoing Way of X series, David's powers have proven to be so dangerous that he has most recently been captured and dissected by Orchis, an organization dedicated to responding to the "threat" posed to the world at large by mutantkind. Though he was unceremoniously killed and subsequently rescued by Nightcrawler, Legion is still untrusting of his own family, as they are of him and the threat that he poses simply by being alive and well. And considering that his time0travel actions inadvertently created the Age of Apocalypse timeline, those fears might not be entirely unjustified.
HOW STRONG IS X-MAN, NATE GREY?
First introduced in Jeph Loeb and Steve Skroce's X-Man #1 in 1995, Nathaniel Grey was created by the Age of Apocalypse's Mister Sinister using the genetic material of Cyclops and Jean Grey. Although he's essentially this world's version of Cable, neither of his genetic parents knew that he existed until he was an adult, since he was created surreptitiously by Mister Sinister to be the ultimate psychic and aged at an accelerated rate.
Nathaniel was born with nearly every kind of psychic power imaginable, from energy-based psionic powers to telepathy and telekinesis that allows him to manipulate matter on a molecular level. He's even being able to travel through and beyond time itself, but he's also struggled with his body almost burning out from holding so much power. Having been made with the express purpose of defeating Apocalypse, Nathaniel's battle with Apocalypse's son Holocaust resulted in both of them being thrown into the primary Marvel Universe. After operating as a hero for years, Nathaniel came to be regarded as a messiah unto himself, though his nearly infinite number of mutant powers almost caused the end of the world in the process more than once.
LEGION VS. X-MAN: WHO WINS?
Although their histories have always been tied to some extent, they didn't really come face to face until the 2018 Uncanny X-Men storyline "Disassembled" by Ed Brisson, Matthew Rosenberg, Kelly Thompson and Mahmud Asrar. Legion and X-Man came to blows with one another within Legion's mind. After discovering he was dying, Nathaniel Grey chose to become as benevolent of a tyrant as possible, and the X-Men did all they could to stand in his way. Eventually Nathaniel and Legion met face-to-face, and before long, X-Man had taken complete control over David Haller's mind and body. While the heroes had attempted to use Legion's mind like a cage for X-Man by locking him in an artificial version of his home universe, he ultimately proved to be even more powerful than the son of Professor Xavier himself. Nathaniel had already claimed other mutants as his own Horsemen of Salvation. And much like Apocalypse had in his own timeline, X-Man began remaking the world in his own image. When he was finally torn free from Legion, it came after being assaulted by almost every other mutant in existence, and it resulted in Nathaniel sending the other X-Men to a reality of his own creation for a time resulting in the Age of X-Man.
While they both are more than capable of bending reality, only Nate Grey has even been described as truly godlike. Legion is without question one of the most powerful mutants ever, but Nathaniel Grey is almost something else entirely. Even though he can't create new powers and personalities for himself spontaneously, X-Man can functionally use his immense to achieve the same effect as almost any superpower. While their battle may not have been a spectacular moment in Marvel history, both of these powerhouses have always been more at home in their mindscapes, and their battle ultimately ended in the only way it ever could.