Four: Brawl
Unless you manage to Brawl with a Sylvanas in play, it doesn’t matter what card wins the brawl, one of the players is going to be unhappy. This is one of the most RNG based cards in the game, and it is basically required in most Control Warrior decks. If your minion wins, you win the game. If their minion wins, you lose it. Sure you can manipulate the outcome by holding on to other removal spells, but the massive difference that Brawl represents in whether it wipes your board or your opponents is easily game winning. Many tournament games over the course of Hearthstone have been decided with this card. While a last ditch Brawl to wipe your opponent’s board and win is cool to watch, it is neither fun nor fair to play against.