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

Okay, I'm satisfied. I rarely say that I like a unit, especially one as complex as this one.

Without Necro-Demons, the balance of power will be disrupted – the seventh-level undead will get only one low-level unit, while the undead faction resembling a dark messiah will get an elite knight. To prevent these sub-factions from killing each other, we need to increase their interdependence – the seventh-level undead will all be flying units, and the Necro-Demon faction will be infantry and archers. Therefore, the flies are now in a suspended state. I don't know how to visually connect them to the seventh level; we can simply accept their connection as a convention, or we can replace the unit with a flying magical skull, or something more interesting.