RTF is a global modification that replaces all towns in the game.

Personally, I see two logical options for how to deal with the skill tree:
1. Don't touch the skill tree at all, because it's a tangled mess, but considering the reworked factions, completely ignoring it is not an option, hence the second option...
2. Overhaul the skill tree and finally make it sensible - balance the number of perks, remove confusing connections between skills, and make leveling up general skills uniform for everyone. Considering that there are 4 elemental magic schools, you can get something significantly different from other projects. Plus, hero progression is part of role-playing – it’s important and far from insignificant. Adapting this part of the game to new factions will only be beneficial – more room for creativity, again, individuality of the project, and deeper immersion in the atmosphere of new events.

Now I want to make each faction playable without the others; therefore, I will have to remove the magic schools and the skill tree, otherwise, it will be complete chaos, and each faction mod will have to include everything mentioned above + files for normal operation without other factions.
The introduction of new schools was motivated by the fact that all evil factions had a combination of darkness and chaos, and most good ones had light and summoning. At that time, we all believed that darkness and light were related to elemental magic as in Heroes VI. Now, I have changed my views and learned more about Ashan.
New distribution of schools:
1 Humans: light-darkness
In principle, everything is correct; the Black Guard constantly uses black mages, while the good mages from Chaos only know Magic Bolt, so light is closer to them (and there are plenty of Elrat churches in free cities).
2 Elementals: light-summoning
This faction is already overpowered; now, I'm giving them back the old academy of magic schools, which makes sense.
3 Nagas: light-summoning
In Heroes VI, Nagas immediately have 3 spirits in their army: Kappa, Stream Spirits, and Snow Maidens, hence summoning.
4 Undead: darkness-summoning
5 Chimera Mages: light-chaos
Here, lore comes to the rescue - creating a beastman or an Orc involved resurrecting an opened corpse in a cauldron with another creature’s blood, so they should learn light magic.
6 Dark Dwarves: chaos-darkness
An evil, vengeful race must be able to curse and kill!
7 Orcs: chaos-summoning
The higher levels of the castle will feature demons, and sorcerers will have the demon summoning spell.

Due to this, amendments will be made, about which I will write later.

Added after 51 minutes
Each castle mod will include a mod that modifies UIGameRoot.(UIGameRoot).xdb, specifically this one.
In the Dark Dwarf Elementalists mod, there will be a dominant version of the mod that overrides others; this is due to changes in territories in this mod.
DefaultStats.xdb will change raising undead and will be included in all mods; Necromancers will raise from everyone, including elementals and constructs, according to their levels, not the old table; the dominant file will be in the Lizardmen mod because it needs to change Blood Wrath in the same file