Press the green flag to start. The A key summons your wand. The L key lights up your wand. The E key summons your trusty patronus: the starfish.
Major credit to @mizzpeters, @ceebee, @asparklekat, and @paulinah for encouraging me to read the Harry Potter series this year. I feel like I learned a TON about reimplementation in this project. (The details: I had initially implemented all of the sensing logic in the monster, but that seemed to be too resource-intensive for Scratch, so I then redistributed the code across the other objects and the project was less laggy.)