Actually, the game with black knights is so easy, that it's laughable. Black Knights + Evlin spell (resurrects up to 30% of the entire stack!) + Splinter of Darkness is a game winner.
As for your suggestion for a playthrough, I quite like it. People can easily challenge themselves this way. Human and Undead armies will be the easiest, as it is very easy to resurrect them (paladins/inquisitors and evlin). Demon, Elf and Dwarf armies will require the resurrection spell, quite some mana and quite some rounds to do a battle with minimum losses.
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