[Shangrila00]

Rust mist comes out at Evo 2, and performs admirably at neutering Ulmish troops at that magic level.

You are talking about a magic dominated battle with level 6 evocations where troops are nothing but chaff. I seriously doubt the marginal advantage of blackplates in the purely chaff role is what played the decisive role. I mean, why was Agartha wasting mage turns with rust mist when he has Alt 6 and thus iron bane?