Z undid the locking spell on the broom shed door. It was a step or two up from that standard ones, but still no real challenge for her. Z had been too advanced for most of her magic classes in the United States and in a fit of pique, her Practical Magic teacher had given Z a set of Byzantine Boxes and told her to undo all the spells during class time just so she'd had something to do and stop confusing the class.
It'd taken Z about three weeks to work through the full set.
So, the spells on the broom shed and then the spells of various personal brooms stored there weren't much of a challenge the first time she'd broken into the shed to "borrow" a broom for a leisurely afternoon ride. Z'd taken to breaking in and going flying as a reward for getting through difficult days, stress relief, and a way to pass time. For all that the school had fallen into disrepair, been trapped and bespelled into something out of a muggle action film and Z was fairly regularly roped into helping clear areas and/or rescue younger Slytherins, she got bored. Hogwarts was located in quite possibly the most boring place she's ever been.
Z was thinking things along those lines (she was also cursing the stupid forest, practice exams, Brendon's inability to sew, Ryan Ross' general existence, Tuesdays, and that really odd dream she'd had about Professors Lazzara and Kitching helping her with her spell work and Nate Novarro delivering pizza...) as she broke into the broom shed again and started looking over the brooms, seeing what looked like a good option.