I've been fiddling with spells and have a question. Am I correct in thinking that the "meat" of a spell is hard-coded and so cannot be changed? I have found that the class/level of a spell can be changed via data\rules\spells\*.txt and the duration seems to be listed in every .py file of the spell. But I can't find how to change values and numbers of the actual spell effects. Tree Shape, for example, drops your dex to 0 while giving +10 natural armor. I would like to change this to +15. Is this possible?
No. Most of the actual effect parts of the spells are hard coded. The example you give with Tree Shape one of those hard coded things. You can however throw in a Barkskin effect, which (if it stacks, not sure on that) would up the natural armor bonus. This is about all the help you will get from me on this project. Probably from all the modders here. We at Co8 are more interested in trying to make this game as rules compliant as possilbe. Your project doesn't really fit into that.