Sylvester,

Right here, Ive been held up by work and the mills seemed to have been down or the libraryserver I sit by must have f***ed up...

About maps, I noticed the planar meeting place thingy, I actually have a world consisting of spheres floating through space and time touching each other and in these periods creating passages through the landscapes...

In practice the world works like this, I had 100 small terrainmaps and each time players entered the edge of a terrain I used dice to decide what map they would enter if they continued to go the same direction.....

From each terrain space stretched infinitely outwards and I you traveled out there you could see all spheres intermingle...

Perhaps dominia (not the same as dominaria) is a dimensional version of that with specificly bound passages (like each world is in contact with 3 other worlds and permanently anchored to them)
To planeswalk through something similar would mean that a person has extensive knowledge of how planes intertwine, thus the difinition PLANESWALKER...

A planeswalker gains power and knowledge by travelling through as many planes as possible.

Think of how rath and phyrexia overlap each other and accesses dominaria, then think of where serras realm where bound.

When weatherlight "jumps" it travels the void between all existing planes, while a trained planeswalker probably speeds through the chains of connected planes in some sort of phaselike manifestation, disappearing, reappearing...

WD