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

Could a Necromancer hero be given the class of Heretic/Cultist? A Necromancer who has switched from worshipping spiders to worshipping fallen angels?

And could fallen angels (of course, the model is already used for the Faceless Ones, but they are changed enough that the similarity wouldn't be obvious) replace the Void Spirits, which could be moved to the 6th level, thus beautifully introducing dragons?