Warden of the Umbral Codex

When Leo, a data-entry clerk whose life is a monument to mediocrity, inherits a strange obsidian artifact from his estranged great-uncle, he dismisses it as junk. But that night, a creature of living shadow tears through his apartment, hungry for the relic. Now, hunted by monsters and thrust into a hidden world of magic and mayhem, Leo discovers the 'junk' is the Umbral Codex, a key to unimaginable power and a prison for a forgotten god. He's not just a target; he's the new, completely unqualified Warden. And the inmates are breaking loose.