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

Here's an idea regarding the Necropolis faction: in all games, Necromancers are debuffers. Maybe we could allow each unit to apply various curses. For example, the first units could apply a low-level weakening effect, while dragons or other powerful units could apply a berserk or distraction effect at the expert level.

Added 1 minute ago
By the way, you didn't respond about the Mountain faction. Do you accept the idea of replacing the class ability "Absolute Defense" with "Terrifying Presence"?