So regarding the current dream shenanigans I've put together a few "rules" that may or may not apply to magery. Kinda depends on the course the story takes. Most terminology is what I've seen to be commonly used (however some stuff I haven't seen a term for yet in the fandom and made up on the spot for this post.)
Mages don't dream, when they rest their minds instead enter an altered reality that is mostly safe called a haven.
Mage Havens seem to be static and don't change.
Mage Havens are in turn interconnected through a series of "rivers, ponds and streams" called the dreamscape.
The dreamscape is not static, and much like a river or bayou, will chane and reshape itself on its own.
The rules of the dreamscape, and the ability to traverse it depends on the mage and their type of magic it seems. (EG Lalli can't walk across the magescape rivers unless he's following in the wake of Reynir)
Non mage dreams do seem to be connected to the dreamscape, but are deeper into the "ether" so to speak and are probably more fluid due to the nature of non-mages dreams shifting and changing.
Mages can enter the dreams of non-mages but due to how deep into the ether they have to go to do this, it's probably dangerous.
Non-mages may or may not be able to enter the dreamscape, and havens of mages (it'll depend on where Minna takes the story I guess.)
I think I hit on the important stuff, anyone seeing any glaring ommisions or problems with these "rules" or terminology?