Does Magister's mod have any new terraforming spells? I was wondering if these changes would affect his mod.
I don't think the change would cause any real problems for me, although I can't be completely sure until I merge my mod with the new implementation.
What are you considering terraforming spells?
High Priests of Winter have an xml-only spell that creates a Blizzard feature on the tile.
Aquilans have a passive effect that calls or creates blizzards, and Auric Ascended has a passive effect that terraforms all nearby land (using the python result of Snowfall Greater as a python prereq for a dummy spell.)
There are no new spells that change the base terrain; however, some of the existing spells have been changed slightly.
Spells now include references to the new types of hell terrain. (Otherwise, Vitalize would always be able to be cast yet never have any effect on Wastelands and Glaciers.)
None of my terraforming spells have <bInBordersOnly>1 limiting them to be used only within the caster's own territory. Instead, their python prereqs prevent the AI (not human) players from using beneficial spells in territory controlled by rival teams.
I allow Scorch to get rid of Blizzards and sea Ice (although the caster would have to have Flying to get a chance to use it on the impassible water feature). I blocked AI players with the White Hand state religion from using Scorch to get rid of Snow or Glacier terrain.
I switched Bloom to work through python instead of XML, so players who do not have FEATURE_FOREST_NEW under <MaintainFeatures> can still use the spell on tiles that have improvements which can ordinarily be built over forests anyway (Camps, Lumbermills, Yggdrasil, Tomb of Sucellus, the Seven Pines, and Nature Mana Nodes in my modmod). Frankly, I think it would make more sense for you to change the DLL so that this python workaround is not needed. (It is just annoying to have to destroy a camp in order to use bloom and then rebuild over it.)
Edit: I just remembered that I also permit Bloom to be used to make Burnt Forests turn into New Forests quicker.