Spider-Man: Brand New Day may have just set up a major Avengers: Doomsday threat

Spider-Man: Brand New Day is the last Marvel movie before Avengers: Doomsday releases on Dec. 18, leaving plenty of fans speculating on how Peter Parker’s latest adventure might affect the upcoming battle against Doctor Doom. Peter has caused some big problems before, most recently when he broke the multiverse in Spider-Man: No Way Home when working with Doctor Strange to make the world forget his secret identity. While Brand New Day doesn’t involve magically conjuring actors from different franchises, it seems Peter has once again tried to solve a problem without really thinking about the consequences. We might see the results of that mistake play out in Doomsday.

[Ed. note: This article contains spoilers for Spider-Man: Brand New Day]

In Spider-Man: Brand New Day, Peter (Tom Holland) starts going through a sort of spider puberty. His arachnid hormones get out of balance, overloading his senses and causing him to grow spinnerets like Tobey Maguire’s Spider-Man in the Sam Raimi trilogy. Peter seeks help from Bruce Banner (Mark Ruffalo), who has taken to wearing an inhibitor to keep himself from turning into the Hulk. Peter uses that idea to develop an inhibitor that would work on anyone with mutated DNA, whether caused by gamma rays, a radioactive spider bite, or having the X-gene.

Peter uses one inhibitor to suppress his own growing powers and another to subdue the telepathic mutant Jean Grey (Sadie Sink). The technology then falls into the hands of the United States Department of Damage Control. They use it to keep Jean under control while they scan her brain to learn how her telepathic jumps work in the hopes of giving that power to someone else.

Power suppression and the ability to mimic mutant abilities are both associated with Sentinels, the robots Doom is seen commanding in the trailer for Avengers: Doomsday. They likely come from another reality given the Sentinels played a big part in X-Men: Days of Future Past, and many of the characters from Bryan Singer’s 2014 film are already confirmed to be returning in Doomsday. But Damage Control could also use Peter’s tech and the information they gleaned from studying Jean and her sister Sara to start building their own Sentinels.

Scared humans make Sentinels to protect themselves from mutants – though the intelligent robots always wind up betraying their creators. Jean certainly gave Damage Control plenty of reason to be afraid by unleashing the Hulk in their facility and nearly murdering the organization’s leader. When MJ (Zendaya) looks at Peter’s suppression tech, she says it’s the sort of thing you’d use on a monster. It might be necessary for Bruce Banner to use, but Peter didn’t really need it, and he was much better off when he embraced the power of his new mutations. His own fear of those changes just created a weapon that will likely have a big impact on the MCU, especially for the X-Men who are getting their own movie in 2028.