As it turned out, the main thing I was counting on happened. We walked into the middle of a centaur ambush, and just as I had anticipated, our dear usurping Headmistress opened her mouth and inserted both her feet. Her loathing of "half-breeds" (half-breeds indeed! Centaurs are, as anybody who's read the standard books would know, a separate species entirely! Did she sleep through all seven years she was at Hogwarts?) made her treat them like something she'd stepped in, and they were Not Amused. I had a hard time suppressing the urge to giggle as she pushed the situation farther and farther, until she set off a full-scale riot. The last I saw of her that night, she was being carried off by the centaurs.