Tip to complete every enemy at every level (espescially the later ones) Deck with kamikazee + parting gift, peasants if you have it or demon worshippers, maybe some of the weaker skeletons. Maybe 3-4 crystal producing cards, lots of gold producing cards, no need for any iron. I call it "ENEMY SUICIDE"
Best decks are parting gift/ kamikaze if you have it, you'll need to get more than one of them if its against more than level 1 enemies since they use those cards. Have a lot of income cards and use demon worshippers, and then let the enemy kill their own portal