The Reckoning War is Marvel Comics' big event for 2022, and its main writer Dan Slott, may have already given fans all the clues they need to figure out its big twist before the first issue even releases. The epic crossover will see the Fantastic Four spearhead the heroes' fight against a mysterious opponent. Slott has built towards this event for 15 years, dropping hints about this cosmic war that will start in February. However observant fans can already guess the secret identity of Reckoning War's villains.
The storyline from Slott has been teased as a return of "the first war in the Marvel Universe." The Watchers will be key players by breaking their vow of non-interference. This is the first clue to understanding what the enemy of the story will be. Uatu the Watcher was recently resurrected in Fantastic Four: Empyre Fallout #1, after being killed in 2014. This was sparked by the presence of the weapons used by the Cotati during their failed invasion of Earth, which apparently predates ancient races. These weapons belong to a mysterious "first race." This race has some connection to the Watchers then (who are supposed to be the oldest species in the universe), and some fans have speculated they are, in fact, the reason why the oath of the Watchers exists in the first place.
Back in 1964, in Tales of Suspense #53, it was revealed that the Watchers, at first, wanted to use their vast power to help other species develop, and they gifted knowledge of nuclear energy to an unknown race, only to find out years later that that knowledge had been used wage war. This led to the oath of non-intervention, and that unnamed race could be the "first race" who is coming back for a reckoning. Furthermore, in an interview advertising the event, Dan Slott said that the idea first came to him from a comic he read when he was eight years old, meaning in 1975. While Marvel published many titles that year, this is a clue. For example, in Captain Marvel issues #38 and #39, Uatu is put under trial by his fellow Watchers and recalls the reason behind their oath. It is possible a young Slott first learned about this from that comic book, a conclusion supported by the fact that Captain Marvel #38 features a recollection of the conflict between the Kree and the Cotati, which was the basis for the Empyre storyline, co-written by Slott.
In that same issue, Uatu also says: "For one of my race, to do anything is a crime beyond reckoning." It seems likely then, that the name of the event is a callback to that sentence, and the Reckoning War has to do with the Watcher's relationship with the mysterious race they interfered with. After all, they are supposed to be as old as the Watchers, making them predate any other known species. This would also explain why the weapons shown in Empyre were both older and more advanced than any technology the Kree or Skrull had. It is also likely that the Watchers did not tell the truth about the fate of this "first race". Perhaps, rather than disappearing in a nuclear holocaust, they were destroyed by the Watchers themselves to cover up their mistake, and are now back for vengeance. This would also explain why the Watchers would take part in this conflict, because they see it as their responsibility.
Reckoning War will be grounded in Slott's current run on Fantastic Four, and it will begin in February with the one-shot Fantastic Four: The Reckoning War Alpha #1. Regardless of how it plays out, Reckoning War's Dan Slott has dropped plenty of clues for Fantastic Four fans to decipher in the lead up to Marvel's next big event.