Ultimate Fantastic Four

The Super-Skrull is wearing a suit which grants him the powers of all superheroes in his vicinity. This protects him from attack while his Skrull miracle pills kill every human being who ever injested one. Soon, the only human left is Ben Grimm. Ben realizes something about the suit, though: the Super-Skrull doesn't have any super powers, and Ben has kept himself in excellent shape. He takes out the Super-Skrull, and then heads back in time hoping to prevent the Skrull invasion from happening.