Through the training, Hermione had shifted her strategy a bit. She’d never fight them off with sheer force, or dueling prowess. She needed to use her intelligence, her number one trait. When they began their duel, Hermione immediately cast a Smoke Charm, covering the immediate area in a thick gray smoke. Harry and Ron fired blindly into it, unable to see. Hermione was long gone, using the cover to gain some distance, and camouflage herself. Then she waited for Harry and Ron to inevitably follow after her.