I always wanted a haunted funhouse style of dungeon. I don't want to go too in depth because it's something I am including in my fanfic. The basic idea though is that instead of the typical dungeon/temple, the doors and stuff wouldn't be locked. That would be because the doors are hidden. Inside of mirrors, behind bookcases, and other places. It'd be a bit crazy too, like how you might see a room filled with stairs, some that are sideways, straight up, upside down, etc..., and the only way to see what stairway another stairway connects to, would be with the Lens of Truth. It would basically be like a 10+ story area. And instead of getting a map and compass, you could maybe get pieces of map requiring a form of decoding, or deciphering cryptic messages to find your way through. There would also be the hint system who would make the journey easier if you really didn't want to go through all of that. Common enemies would be more funhouse style. Maybe mutant jack-in-the-boxes or painting ghouls. I mostly just think it would be fun.