Warning! Spoilers ahead for X-Men #4
In the latest issue of Marvel Comics' X-Men, Jean Grey continues to prove her abilities as an omega-level mutant, making her a Superman-level hero despite no longer having her power from the Phoenix Force. Ever since she and Cyclops have been leading the latest iteration of the X-Men, Jean has had several moments where she's used her telepathic ability in all sorts of new ways. Furthermore, she's also proven her strength against several formidable foes such as Knull the Symbiote God during Marvel's King in Black, and this new issue sees her handling one of Doctor Strange's more fearsome foes with relative ease.
In recent issues of X-Men, Jean Grey has been helping Scott Summers lead this new team comprised of Rogue, Synch, Polaris, Sunfire, and Laura Kinney's Wolverine, operating from their new base known as the Treehouse in Central Park. After they've already dealt with a couple of alien invasions as well as the High Evolutionary, X-Men #4 sees the team asleep in the dead of night while one of Doctor Strange's longtime foes revels in his new free reign due to the Sorcerer Supreme having recently been murdered.
Known as Nightmare, X-Men #4 from writer Gerry Duggan and artist Javier Pina sees the demonic fear lord preying on the dreams of New York's citizens, though he can't help but dig through the minds and dreams of the X-Men in their new headquarters as well. While Doctor Strange would have normally stopped him, it's instead up to Jean Grey. While Nightmare underestimated her, he soon realizes that doing so was a grave mistake he won't soon make again. Using her omega-level telepathy, Jean was able to battle and repel Nightmare while also showing him just how insignificant he was compared to her own strength and power.
After literally smacking the demon upside the head, Jean Grey chose to offer Nightmare mercy, at least this time. Before she sent him back to his realm, she warned him that she now had his scent and that if she ever caught him preying on the dreams of her team or the people of New York, she would end him. While it's seemingly been established that Nightmare will always exist so long as there are people who dream, Jean's warning didn't seem to be an empty threat. Perhaps she really could destroy the fear lord if she wanted to, which is certainly impressive and further proof that her power levels are on par with the Man of Steel (if not more so).
When it comes to the most powerful heroes in the Marvel Universe, Jean Grey is near the top of the list. There's a reason she was chosen by the Phoenix Force as it recognized her power and strength, adding its cosmic powers to what she'd always possessed as an omega-level mutant. It's nice to see that Jean is just as capable and powerful as Marvel Girl as she was as the Phoenix (especially considering the greater level of control she has). It's going to be interesting to see what else Jean Grey will do with her Superman-level powers as X-Men continues.