Suiting Up — Richard Lee Byers

Matt Brown lives in a world of superpowered heroes and villains, of mutants, sentient robots, and monsters, but none of that has anything to do with him. He's an ordinary guy living an ordinary life...until alien invaders lay waste to the Earth, and all of humanity's costumed champions go down fighting. By chance, Matt falls heir to their powers, but what how can one fake hero save the world when the real ones already failed? The search for an answer launches him on a journey through a post-apocalyptic nightmare where alien horrors and human supervillains battle to rule the ruins.

The Impostor is the new superhero saga by veteran fantasy and horror writer Richard Lee Byers, a frequent contributor to the Forgotten Realms series of novels.