Frida's Dilemma - "Duncan" [Campaign 1, Mission 3]

It definitely won't work on the first try. I also initially tried to develop my city, gather troops, and then it turned out that Duncan's troops were much better developed, very good compared to mine, so I just stood there and watched as he crushed my army; he had much more initiative than I did. As for the armies, I don't remember exactly what they were; I last played the campaign about three months ago, so I've forgotten a bit. I also used the "Blinding" spell against the Adepts.