I dont play age 2, but on age 1, i send 25k archers/2k bali and 1 of each foot troop to vallies for medal farming....i lose very few archers and get decent amounts of medals...not always nation or justice though. Nowadays i only need nation medals to persuade heroes. You can use 1k bali instead of 2k, it just makes the chances greater for archer loss. I find level 10 forests best for nation medals. If you choose to send the balista to medal farm, make sure the valley is relatively close...or it will take forever to get there and back. This may have no relevance to age 2 at all...in that case....sorry