But based off of all that speculation and running with the lantern idea...

How about the mistlands due to being perpetual night and in a dense fog is basically just blindly wandering around unless you have the Yag Lantern that will clear an area around you.

Frankly I expect to not enjoy the mistlands much as I do like the environments and seeing them... the whole fog thing while quite atmospheric is just much less visually appealing to me.

That said though the limited visibility area could allow them to increase enemy spawns without impacting performance too much if they don't have to be rendered that far out from the player. So more "swarming" types of enemies like the bats/skeletons but in greater numbers.