[Squirrelloid]

Immaculate: W4 permits Streams from Hades with D1, which is a great place to pick up good D mages (without spending D gems).

Baalz:
You missed one of the alt gems. Earth Meld absolutely destroys KotD. Combine with boil for some killing while your troops dish out some damage. Obviously lay out some other stuff too, but if you have a couple mages doing nothing but spamming earth meld they're going to pull their weight.

Beating Oceania requires leveraging significant mage resources. But it can be done.