Um, how about Old Grehk, Thalmarkin and Melhed together? The horrors are nasty but those three realms can put an awfully big force in the field, plus whatever the other three realms can drum up. Fronen and Sint can now recruit again, though in Fronen at least we have very few RCs to recruit from thanks to the semi-blight. It certainly won't be easy, but it's not impossible.