A silent Protego deflected the girl's feeble spell into a bystander. Despite wanting to linger to play, she could feel the beginning twinges of the polyjuice fading away. Her Lord would not be happy if she was spotted in Diagon before he gave the word. As it was, there would be only the bloodtraitor's spawn's word to say she had been here.
But there was time for a few more taunts and a spell or two.
"Is that all you have, little baby Nymphadora? You need to study up before we finish this dance." Another explosive hex destroyed a vender's stand and a blast of pure flame had the protective charms beyond it burning merrily.