Saga of the Soul Dungeon
B67/100Web serial by AJFoxmoor
When Caden dies in an accidental fall, he is merged with a dungeon core in another world. He's not particularly happy to be dead, so resurrection in any form isn't too bad. The real problem? The dungeon core wasn't dead, and he has to share mind-space with it. That doesn't even account for the powerful wizard who is understandably reluctant to let a dungeon escape. And even once he manages to escape, he must found and manage a dungeon in a location fraught with complications: it sits on the border of two rival human nations, a sentient plant race claims the ground as sacred, and teams of adventurers keep wandering in looking for a living. Through it all, Caden is determined not to lose his humanity and become just another murder-hobo dungeon.