Let’s come up with a monster.

I think we can create several sub-factions. Like a Jungle race - the aborigines of the dark jungles. It would include: an aborigine, a shaman, a mindi (giant snake), a rainbow snake, a lion-headed creature, a wollop (tiger-bear), a bunyip (tiger-snake), a bandicoot (a rhino with a snake on its tail and bat wings). Or Tundra - inhabitants of the northern plains. It would include: a snow warrior, a snow shaman, a yeti, an ang'yak (in Chukchi mythology, the spirit of a dead child left near the snow), a horker (giant seal), a remorhaz (snow worm). You can't play as them, but you can capture their cities and subsequently recruit troops there, plus each city brings 500 gold per turn.