Dead? No, I'm the Abyss Lord!

Yenvar wanted to go up as an adventurer alongside Seyora, the woman he trusted. She and the party he ran with robbed him instead and left him for dead in an underground dungeon. Down there he wakes the Dungeon Lord system, which lets him command the monsters in it, and he uses it to hunt down the adventurers who put him there one at a time. After that he changes class and registers as a Hero. Seyora got away, and she comes back with the name of her family behind her and imperial troops with her. Yenvar handles them from inside his position as Hero, working alongside the soldiers while quietly taking full control of the dungeon under their feet. Moving with the army shows him what it does. The empire's grip on ordinary people is worse than what he was told, and the garrison starts putting together who the Dungeon Lord actually is.