It seems Dirty either didn't see this topic or, if he did, he wanted people to think about it.
Second option: Tazar, level 108, and a Potion of Life. With this setup, any number of any creatures will deal 1 damage. The Efreet should be able to handle it himself. I haven't tested this in practice, but in theory, that's how it works. If you calculate how long this battle would actually take, the Efreet will likely die of old age.
Third option: If this is allowed, the dragons should be in the town but without towers. We use Müllich and artifacts to gain speed and push against the gates. We also take a cannon and a cart. The hero should have the skill to control the catapult so that it doesn't destroy the walls.