Haven – "Everything is mixed up, truth and falsehood" [Campaign 3 – Mission 2]

I also can't seem to beat this mission. I tried to quickly capture cities, like with the Necropolis, but it doesn't work. I captured Ivian and drove Cordelia out of Whitehaven, and that's as far as I can get. Cordelia keeps defeating me with 850 arbalests, 1100 sisters, and 285 griffons. I even have 380 knights, and I cast Aura of Retribution on them, but they still defeat me. Maybe I should finish off the undead first? But even then, I'm stuck. In the dungeon of Zaim, I'm fighting, trying to get past the gate, but it says I need to pass the trials of the knight-dragon, but where do I even find him? And voices whisper, "Find the knight-dragon."