Contains spoilers for Sentinels (2024) #1!The X-Men’s newest team of complicated villains have made it their job to capture the worst of mutantkind, but they might have just bit off more they can chew with the return of one of the franchise’s most powerful villains who once beat the Hulk, among others. If the Avengers had to put their lives on the line to win the first, time, do these traumatized soldiers have any chance?

The new book X-Men book Sentinels (2024) has just revealed the terrifying villain they’ll be facing as the team’s newest member Drumfire sees Onslaught after first activating her new powers.

Onslaught, perhaps the most 1990s comic book villain of all, is a psychic being made of all the worst thoughts and impulses of Professor X crossed with Magneto’s own evil. In the famous Onslaught Saga, only the seeming sacrifice of all the Avengers and The Fantastic Four were able to stop it, meaning that the new cyborg Sentinels will have their work cut out for them.

Sentinels marks the return of Onslaught, the ultimate X-Men villain of the 1990s

Sentinels follows the adventures of the titular team of cyborg soldiers who’re supposedly the successors to the classic mutant-hunting Sentinel robots. Headed by Lawrence Trask, son of original Sentinel creator Bolivar Trask, the team are working to capture the deadliest of mutants to bring back to Graymalkin Prison; the former X-Mansion which has been co-opted into a mutant prison. After a breakout at Greymalkin, Drumfire activates her energy redirecting powers to kill Omega Red but instead of a charred skeleton, what she sees is Onslaught standing in the wreckage of Red’s body.

Onslaught most recently appeared in the miniseries Way of X and its one-shot conclusion, X-Men: The Onslaught Revelation #1, where he was inserted into the mutant nation of Krakoa by anti-mutant coalition Orchis in order to kill the island from within. In Way of X, Onslaught hid via anchoring to the emotion of hate itself, the hate felt by the mutant Lost towards Fabien Cortez. Onslaught could be doing the same thing to Drumfire in Sentinels, co-opting one of her emotions to survive. Onslaught was defeated in Onslaught Revelation by Krakoan Unity, but this new team is anything but unified.

Way of X and X-Men: The Onslaught Revelation #1 are written by Si Spurrier, illustrated by Robert Quinn, colored by Javier Tartaglia and lettered by VC's Clayton Cowles

Onslaught's apparent reappearance might be a little more complicated than it seems at first

It’s also possible that Onslaught isn’t really there. One of the core conceits of Sentinels is that its cast are Drumfire's mother was killed in the original Onslaught event, so she might be having a traumatic flashback. It’s also possible that this is a side effect of her cyborg augmentations. The issue highlights the augments’ sensory side effects multiple times, and Onslaught’s appearance could be a new manifestation of these side effects, but that doesn’t mean that this manifestation isn’t dangerous.

Just because Onslaught might be imaginary, it doesn’t mean that it’s not real. Onslaught is a being made of pure thought, and it’s resilient enough to survive inside emotions themselves. Regular rules don’t apply to someone like Onslaught, whose powers and exact nature are basically made up every story. Why couldn’t it create or recreate itself through a traumatized cyborg whose own brain is being experimented on? The new Sentinel program has aimed to create soldiers strong enough to stop the X-Men, but they might have just remade something much, much worse.