On January 1st, 2020, the comet hit, and a good chunk of the people on Earth died or turned into mutants. But some people gained powerful magical abilities.
You would think that the fall of humankind would usher in a time of peace and happiness for the survivors, but since powerful people tend to be assholes, life got worse, and these mages enslaved those who couldn’t protect themselves.
I have magic too, but not just any magic. I can summon guns, and nothing kills asshole mages better than a bullet through the brain.
Disclaimer: this is a slow-burn harem series with explicit sex scenes.