Barely made it through... 9999 rusty dragons in seven or eight stacks, and the Evil Emperor with over 7000 archdevils. Of course, the battle was against a superior force, but... the Evil Emperor has "the power of the father of dragons," which means you can't berserk, blind, or clone him, and then massively revive him with archangels. So, there's no way to come out of the battle unscathed.
I defeated the rusty dragons (who were hiding behind centaurs) using a force field and came out of the battle unscathed . I didn't bother to attack the dragons in the other squares, as I didn't see the point.

And here's the battle between Vidomina and the Evil Emperor
For professionals, these battles are just a warm-up, but it took me a while to win...

Pomazok1329 and igrik, thank you both for suggesting these maps. I'd like something similar to Warlords or The Darkness Attack.