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

You could cut out the texture of the Phoenixes from the sixth game and call them Thunderbirds.

I thought about that, but I don't think it's a very good idea because there's nothing to attach it to. It would be better to extract the Air Elemental from there, give it a different name (Storm Lord, Lightning Master, Electrone), and put its texture on the Lich.