I wonder if dream worlds aren't a little bit like... actual dreams? As in they change a little bit here and there. I've nudged a little bit on lucid dreaming and ones surroundings are... not very consistent at all as far as I've seen.
I guess if I had a dream world, it would be a little bit like that, some sort of amalgam between re-occurring dream scenes I've had as well as places that have mattered to me. But all dream world we've seen have looked like people's home areas so I guess mine would, too.
Which would make my dreamworld based around the natural reserve behind the neighborhood where I grew up. More specifically the ravine and its little creek that would run out into the Swedish archipelago with a small beach on one side, surrounded by softly rounded stone hills. On one side of this creek was a small path; on the other side was a pretty high mountain wall. In reality there is an oil cistern on the top of that little mountain, but I imagine that in my dream world, it would probably melt into the various little summerhouses that have been owned by my grandparents, much like geography in dreams doesn't actually make any sense. So that would take me to at least four different locations that... wouldn't necessarily fit together
One lot in the Stockholm archipelago; one in the archipelago of northern Sweden; one on the mountain plains by a lake; and one to a sheep farm. In between these places would probably be filled with *actual* dream stuff that randomized and changed like dreams do, as well as at least one tree leading underground.
Anyway, that little creek had a small beach right next to it where stuff would always wash up, and I'm playing with the idea that if I were an SSSS mage and could predict the future (because I'd definitely be part of the Icelandic school of magic, I never knew much about the Finnish lore) I'd do so by paying attention to whatever washed up at that beach.
I'd make myself a small house at the bottom of that creek, if I could. It was always very overgrown and sheltering and I'd go there when I was feeling down. Something tiny and quiet with room for a fire, like this: