[PvK]

One idea is the Sub-Worlds could get strong thematic defenders throughout, rather than at the portals. Otherwise the portals can be bypassed e.g. by Stealth. Still if the sub-worlds are worth it, people will teleport and cloud trapeze in SC's...

Another idea is fixed balanced placement locations and victory locations might be able to make it more balanced.

Another is to to make the Sub-Worlds less worth conquering, or the rest of the provinces more worthy of conquest, somehow.

Just some thoughts.