Instead of using Unicorn Mustang, try Stone golem. It will reduce the damage taken. If the cards have the snipe ability, Centauri Mage should take care of the issue as it has 9 Health and the "Return Fire" ability. If you don't have enough mana for Centauri Mage, try using Earth elemental as a"Sacrifice" in second position. It will give you enough time to deal with the other cards.