Rolling his eyes, Harry started to chant, and from his position, Snape could see the strain the spell was causing. All three teenagers were heavily affected. Ron was clenching his teeth. His complexion became waxy, and he started to sweat. The redhead was clenching Hermione's hand so firmly, both of their fingers were turning white. Severus fought against the binding, tried to intervene, to stop this madness, but his master's command rooted him on the spot. The longer the spell lasted, the more the Potion Master started to hate the teenager for it. Then it was over, and Harry sank back on is haunches, breathing deeply. Ron broke to his knees as well, taking huge gulps of air. "By Merlin, let's never do this again."