Ranger – “Defense” [Campaign 5, Mission 3]

I played as Feday and left a purchased hero in the Castle, giving him all the archers and druids. He held the defense perfectly while Feday conquered the second Castle and started destroying the garrisons. Then, I freed the heroes, teleported to the capital, transferred the troops, and that was it.
As for the dragons guarding the Dungeon, there were 12 of them, and they scattered.