Warning: Contains spoilers for Fantastic Four #40
The Reckoning are the Marvel Universe's latest villains, and they are essentially a reverse version of the Watchers, which makes them the most dangerous foes to appear in a very long time. The Watchers are one of the most ancient species in the universe. Originally known as the Luminous, they reached such a level of technological and spiritual development that their power surpassed even the gods. They also wanted to share their knowledge to help other species develop, so they traveled to distant planets and shared their «gifts» with other species.
One of these «first races» were the inhabitants of planet Prosilicus, who gladly accepted the Watchers' gifts, but used them for something more than intended. They made weapons and created an intergalactic empire built on conquest and enslavement, to the point that the other species called them the Reckoning. When every civilization united to stop the Reckoning, the «first war» erupted, and it ended with a "last resort weapon" unleashed (it is still unclear by whom). A lethal amount of cosmic energies was released that turned nine-tenths of the universe into a toxic wasteland. The Watchers were forced to intervene and created a barrier to seal away the contaminated part of the universe, together with the Reckoning. After that, they vowed to never interfere again in the affairs of the universe.
Related: Fantastic Four Reveals Exactly How She-Hulk Caused the Reckoning War
In the first account of these events, in 1964's Tales of Suspense #53, by Stan Lee and Larry Lieber, the Watchers gave the Prosilicans the gift of atomic energy. In the 1960s, with the «fear of the bomb» running rampant in the Cold War climate, that made sense,
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