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

Minotaurs from Heroes 7, hydras from there as well, and perhaps griffins from the Chaos mod. Cyclops from Heroes 7. Manticores from the sixth game (the manticore was brought from Persia to Greece by Ctesias of Cnidus, who also wrote about the manticore). You can add many more. Medusas, genies, Mormo, and empusas...

This is an exaggeration; you need to choose popular units that everyone knows and remembers for the faction.

For example, a satyr, a harpy, a minotaur, and another flying unit are needed, plus 3 Greeks. You could, of course, put a hydra on the seventh level, but then the faction will only have one flying unit, and it won't be the best one; the fourth level is the limit for a harpy.

Manticores are not associated with Greece (at least not for me), and people won't accept griffins and cyclops – when I put griffins with the dwarves, I read that it was a bad idea and that griffins belong with humans.

A Greek cyclops is a person with one eye; it looks good in the third game, but I think it will look strange in the fifth.