The music for this scene should be dark and dramatic, reflecting the horror and suspense of Snape’s transformation and the ensuing fight. The music should use low-pitched instruments, such as cellos, basses, and drums, to create a sense of tension and danger. The music should also use dissonant chords, such as diminished or augmented triads, to create a sense of instability and chaos. The music should have a fast tempo, such as allegro or presto, to match the pace and intensity of the action. The music should also use sudden changes in dynamics, such as crescendos and diminuendos, to emphasize the impact of the spells and the blows. The music should have a minor key, such as C minor or D minor, to convey a mood of sadness and fear. An example of a piece of music that could fit this scene is “The Battle” by Hans Zimmer from the soundtrack of The Lion, the Witch and the Wardrobe. This piece of music has all the elements described above, such as low-pitched instruments, dissonant chords, fast tempo, sudden changes in dynamics, and minor key. It also has a dramatic and epic feel, suitable for a climactic scene.