Walkthroughs for custom maps.

He was wearing armor, but this jerk liked to cast Mass Dispel or Healing, even if not at the beginning of the battle, which made the armor less useful.

For me, the armor was useful because archers move in 1 turn, so slowing and other effects from AotD work without spending mana or casting in the first round. After that, you can cast Berserk or something else useful for winning...
And the AI is stupid: if you cast AotD on it, but don't overdo it with buffing your units or further worsening its stacks, it acts very foolishly and doesn't remove everything with a dispel or healing...
It can also be passed without Fire and Expert Berserk, but I would even then prefer to take Intelligence instead of Ranged Attack.
Or not take Attack, but take Ranged Attack, but I haven't tried that, as there are only a few ranged units at the beginning, and the focus is still on melee combat.