Call it "double or nothing", either player, and the winner gets to pick another card from the losers hand. If the player who didn't call it wins, they get to pick two more cards from the other players hand.
If you hold on to all your Unicorn and get 3 of them you win automatically....
Any player not part of a battle can place a card face down before a battle and see if they can take all the cards. Once the battle cards are played, the hidden card is turned over and if it beats the other two cards that player than get all three of them. No playing the thief or health cards.