As for her high marks in the  supposedly easy subject of charms, it was definitely paying off as she removed the acrid smell of cauterized flesh from the makeshift hospital that was the Great Hall. Dark Magic had been used extensively in the battle, and many curses were twisted specifically to not heal on their own, and resisted normal healing spells. It was a horrible solution that most Healers would not have considered, rather letting the corruption slowly creep across the body as a slow-moving cancer that would eventually prove fatal; but Poppy saw the results and agreed that Narcissa's radical treatment was for the best.