Kevin saw her get hit with the slashing curse, but managed to avoid his other hexes. He admitted to himself that she was good... but wouldn't dare tell anyone else.
He went into a roll just as the blasting cure hit. He came back up on a knee, glaring at her. So, she wants it rough, eh... He saw a lone DE close to her, and sent his 'brick wall' hex at him, giving her a reminder of what he could do to her.