With 2 or 3 players, when games are fast and furious, playing multiple games is particularly fun!
Play the first game as usual. At the end of the game, count the cards in your score pile. One player must write down all the players' scores.
At the start of each following game, during setup, the player(s) with the lowest overall score turns one extra card around in their hand to face themselves. This means they will be able to see the fronts of two of their cards when they start the game (instead of one).
The player who is currently winning goes first. If players are tied, the oldest tied player goes first. After three games (or as many as you decide to play) add up your scores, and the player with the highest overall score wins and is declared the Wizarding Champion!