"Now." Harry and Neville both shouted the knock back jinx's incantation. Two jets of light flew from their wands and slammed into the troll, which had been mid swing. This meant it was already slightly off balance which is what Harry had been counting on. It staggered backwards, dropping the club and the moment the club hit the floor Ron shouted for them all to run. Dropping the shield charm the group of terrified children sprinted past the troll which was focused on reclaiming its weapon. The rush of adrenaline meant no one noticed the two teachers which had appeared at the end of the hallway; they were running too until Hermionie ran full speed into Professor Snape.