Adept of War

Ugh, I can't seem to defeat them the easy way. It's all because they destroy the ammunition cart... Even if I block one of the units with crystals, it still doesn't work.
As an option, you could level up the hero's "Herbalism" skill (for fast casting), find the Sar-Elam ring, and equip the dragon set to increase the units' initiative.
Or just find some Furies, bring the situation to the point described above, and then activate auto-battle... for a couple of weeks...