Quote Originally Posted by .DarkFighter. View Post
i heard chance of getting medals is a lot less if u have no losses.
In my experience which may differ from yours, getting the attack to minimum size necessary to do the job, appears to have an impact on drops.

Sometimes it is just luck, 3 medals from 3 runs. Keep watch on the number of rounds and drop archers by 500 at a time. Change heros, if nothing happens after a few runs.