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

There are two tactics for completing this scenario: slow (gathering an army, training troops) and fast. I completed this scenario at a moderate pace. I had two heroes and all the captured castles. But the most important tactical trick was to attack first with one hero, and then immediately with the second; this way, Duncan won't have time to restore his mana after the first attack. It is also important to position yourself correctly in the passage. It is best if this is done with Zealots. They will hold back the knights trying to enter the door for a sufficient amount of time. Do not cast Blind on the Adepts until you have killed the Paladins; otherwise, they will quickly activate Lay on Hands.