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

What version of the game and difficulty level are you playing? Which week are you in when there are so many dragons? I first captured the Elven Castles, then the Necropolis, then freed the prisoners, and only then did I focus on leveling up the hero and finding upgrades. I freed the first prisoner in the Dungeon. I don't remember when the hero reached the maximum level.