“Heroes of Might and Magic V: Tribes of the East”

A very important question. How do you win the automatic battle for the Orcs in the final map of the Stronghold faction? I'm not talking about the moment when you manage to stop the hero rushing into battle. I'm talking about the battle with the troops that the Shaman has.
I've been playing for a long time, and so far, I haven't encountered this problem. Mainly because the Shaman lacks magic. Also, it's a disadvantage that with the upgraded "Battle Machines" skill, you don't get either a cart or a ballista.
If anyone has a video of this battle, I would like to watch it.