Harry Potter and the Half-Blood Prince

After you join the Duels Club (According to the plot of the game), you will see a board with a choice of tournament. There are 4 clubs in the game - Gryffindor, Hufflepuff, Ravenclaw and Slytherin. You need to pass all tournaments in one of the faculties with the highest score (5 stars). Also in the main menu of the game, in the “Clubs” section, you can go to all types of competitions (Potions, Duels and Quidditch).

You don't have to get five stars. It is enough just to win all available matches with any score.