I'll repeat, perhaps...

Create the following add-on for the HD mod:

1. You build a Mage Guild in some castle and receive certain spells.
2. When building a Mage Guild in another castle - you ALWAYS receive at least 1 new spell at each level of the Mage Guild compared to the construction in the first castle.
3. When building a Mage Guild in a 3rd, etc., castle - you also ALWAYS receive at least 1 new spell at each level.
4. This continues until all possible spells have been learned. After that, naturally, there will be complete duplicates across all levels of the Mage Guild.

Thus, we get the following picture:

1. Classic SoD (with chains of suckers to banks in distant zones, etc.) is not broken at all. The game remains absolutely the same. "SoD players" are happy.
2. control is definitely found not in the 2nd, but rather in the 6th castle. "WT players" are happy.
3. Additionally, the game becomes even more strategic from the point of view of defense and capturing seemingly non-essential castles.