Something snapped in the air. It was like a thunderclap. It rolled for about thirty seconds, raging up and down the corridor like a violent echo, tearing off ragged strips of wallpaper, wrenching down curtains, scarring the plaster on the ceiling, which fell like rough, angry snow all around them. Then suddenly Enola, Neville, Angharad, Myfanwy, and Enola's friend Cassie were crowding in the hall. All had their wands drawn and the combined pulsing power turned the air positively sub-tropical. Neville and Enola cast a powerful dual Shield Charm around them, encasing them all in a shimmering bubble.