The inspiration for this book is a series called Super Powereds by Drew Hayes. It's a novel about a world where some supers are too strong to handle their powers. Eventually as I created this character by applying as many powers as possible while condensing it under a single umbrella, it became its own fictional universe independent of characters like Jack-of-All or Legacy or Titan or Ettin.

The idea in specific comes from the classification of damage potential of supers with the strongest being Armageddon class. At the end of the series we learn that its due to the scope of a power that makes someone a powered. So what if you had an Armageddon class summoner that was also a powered due to him summoning an entire multiverse with the only inhabitants being Armageddon class supers? Obviously since he can't control it there will be massive amounts of damage, but if there's a mind like to what causes the damage maybe the power would be contained if he's in a good mood. In the epilogue a procedure is released that lets your body learn how to control your power. Its also heavily implied that your body naturally evolves to let you use your power.

If Jeremy's summoned gods were immortal what if his body changed to make himself immortal too? What would he think if he was the Last Immortal?

This is my interpretation of the downside to an eternal life caused by a power fantasy.