Awakened As A Dungeon Core?

What happens when a normal man awakens in a world of magic and monsters? What if he awakens as a gemstone that can't move, eat, or communicate but is somehow alive? What happens when this stone learns to cast magic and create rooms, to bring life to monsters of its own and defend itself from invaders? This is the story of that mans journey from a small one room tunnel to a magnificent challenge to the universe. — Description from novelcodex.org