"You can screw up with any spell, but some spells are easier to mess up than others. If you're like, 'Okay, I'm going to go to Brazil', but you've never been to Brazil and you don't know anything about it, so you just picture some random rainforest you saw in a movie once, it's like... The spell doesn't complete? The magic doesn't have a predictable outlet, so a lot of times it'll backfire and hurt you." She shrugs. "Most of the time you'll end up somewhere else, though."