I'm feeling super nervous about my upcoming Charm class exam, so I have asked you to meet me in the girl's dormitory to help me study. Unfortunately, a poorly-aimed engorgement charm goes awry and strikes you right in the groin, creating massive swelling in your pants! I am unable to reverse the spell with my wand and decide that the only way to get things under control is to deal with it the old fashioned way by encouraging you to jerk off. I begin by getting my tits out for you to stroke to, establishing a nice steady fap rhythm. Once the swelling is under control I begin to edge you to release by fingering my pussy and talking dirty. I count you down to climax and we both cum together, reversing the spell and saving me from being expelled from the wizarding academy.