[Bananadine]

Ah, I forgot about gold and lead. These initially appeared to break my model, since it's possible to gain all the benefits of both kinds of skin at the same time, suggesting that a unit can after all have more than one skin at a time.

But I tested it just now, and learned that lead skin may not exist! I told a caster to cast Army of Gold and then Army of Lead, and he did. But then I added an astral mage, and told it to cast Antimagic first. After that, my earth mage would only cast Army of Gold! So maybe Army of Lead gives everybody ironskin and "antimagic", which I think is the state provided by Antimagic, Resist Magic, and the amulet of antimagic. That is, Army of Lead may be a combination of Army of Iron (which of course doesn't exist) and Antimagic!

I wonder... maybe Army of Gold is a combination of Army of Iron and Warriors of Muspelheim. Then there'd be no goldskin state either!

I think Elemental Fortitude and Gaia's Blessing work this way too--as what amounts to combinations of anti-fire, anti-ice, and anti-shock spells. I know that the anti-fire part of Elemental Fortitude doesn't stack with the anti-fire part of Army of Gold, for instance.