Already her concentration was wavering. Fiendfyre was a difficult Dark spell to cast in the first place, but to control it was even harder. Most died in their first attempt. She was grateful that she'd had a good teacher in Felix. Dropping the fireball on his desk, she knew that she would have to leave the building quickly lest she get caught in the inferno herself. The flames overtook his entire desk, jumping to the fabric of his robes. His screams were loud in her ears as she calmly walked out of his office.