Katie felt the force of the stunner that he'd shot at her as she managed to maneuver out of it's way and blew past her. She smirked when the slash hit it's mark, not exactly where she'd planned it, but well enough.
She arched an eyebrow when he began taunting her, reminding her of her quidditch days. But she shook her head, now wasn't the time for happy memories. And she drove her broom down diving out of the way of the unforgivable he cast at her.
She pulled up quickly and turned so she was behind him, and in the few seconds it took for him to turn around she sent a blasting curse at his back.