Księga Czarodzieja (Book of the Sorcerer) - a Polish mod that adds factions.

How do you cut out the Incubus and Ice Demon separately?

well, I'm afraid no one will help you with that, you'll have to dig them out yourself, because poking around in a mod is tedious

each xdb file is a text file with links and settings; here are the file schemes from Esto100nec1, I've crossed out the files that don't need searching because normal people don't change them

I'll note for myself that effect files are usually located in one folder, so you MOST LIKELY won't have to search for them

in an xdb file, links to other files are written like this:
<фигня="фигня.xdb#xpointer( фигня)"> - this means that the FILE FIGNYA.xdb is in the same folder as the file you are looking at
<>folder with fignya/ФИГНЯ.xdb#xpointer(/ФИГНЯ)"/> - this means that the file ФИГНЯ.xdb is in a new folder, which is located in the same folder as the file you are looking at
<>/folder with fignya/ФИГНЯ.xdb#xpointer(/ФИГНЯ)"/> - a slash was added at the beginning, which means that the file ФИГНЯ.xdb is in a new folder, which is located in the mod

it turns out the Estonian has many good documents on file structure; now I'll be sending them to people who ask to be taught Modding) because modern modders don't understand how anything works at all! I always knew that my knowledge of Modding is like a Mechanicus's knowledge of science (not great), but sometimes I feel like a Magos talking to a servitor....