Walkthroughs for custom maps.

I haven't looked into it much. There's probably another option, although it would require quite a bit of effort. We generate a Heroes of Might and Magic IV game with a clone and something non-combat. We feed the enemy hero with purchased heroes. We choose the "Advanced Wisdom" upgrade for him. We give him a castle, and the next day we attack him in the castle. We kill the catapult and live off the elements. The computer can only cast the clone spell, and we berserk it.
I haven't had time to test it, but it looks feasible.