From the publisher's website:

The forces of evil are threatening to overrun HOGWARTS™ castle in this new cooperative game! It’s up to four students to ensure the safety of the school by defeating villains and consolidating their defenses. Players take on the role of a HOGWARTS student: Harry, Ron, Hermione or Neville, each with his or her own personal deck of cards. To secure the castle from the forces of evil the students must work together to build more powerful decks using iconic Wizarding World characters, spells, and items. Defeat all the villains including He-Who-Must-Not-Be-Named and win the game!