Hermione's Shield Charm was immense. It deflected Dumbledore's ferocious spell, but the strength of it still pushed them back several feet. Her voice woke Harry from his stunned torpor, her protective intent infusing him, her terror inspiring his imperative to defend her. He forced the searing pain in his scars to fall away to mere background burning, pulled open the doors to all his mind plains to store it, if that's what it took. Cogency rushed back to his senses ... but there was another of those energetic build-ups on the air, another spell was coming. Harry wasn't sure the Shield would hold this time.