Surviving as a Dungeon Core

I was a normal guy. Then I drowned. Great news: I got a second chance at life! Bad news: I’m not a human anymore. I woke up as a Dungeon Core. No hands. No legs. No food. No way to complain. Just a glowing rock sitting underground with a system telling me I need to build a dungeon before adventurers find me and turn me into a magical battery. Seriously? I survived death just to become a monster’s house? Now I have to create floors, make monsters, set traps, and somehow stop a bunch of greedy heroes from breaking into my home. I wanted a peaceful second life. Instead, I became the final boss. ...Oh no. — Description from novelcodex.org