The player reports their new skills to their House Prefect and is asked to duel Rowan for practice. The game offers three choices for how to duel: Sneaky, Defensive and Aggressive. Both Rowan and the player choose one of the three; depending on the choices, one will defeat the other. Having won the duel, the player finds Merula bullying Ben in the courtyard.

Merula attacks Ben with a spell and the player feels they have no choice and have to decide on the way they will intervene. They have the choice of attacking before Merula or defending when Merula attacks them. Merula and the player then duel and the player will win. Professors Snape and Flitwick then arrive and Snape blames the player for beginning the duel.

However, depending on the earlier choice of the player Flitwick will ask the player whether they were the one who began the duel. If they had not Flitwick will defend the player and Snape will demand the player receives detention anyway for learning defensive spells.

(im just copying them for the hp wiki now ;-;)