“Harry uttered an inarticulate yell of rage: In that instant, he cared not whether he lived or died. Pushing himself to his feet again, he staggered blindly toward Snape, the man he now hated as much as he hated Voldemort himself —
“Sectum — !”
Snape flicked his wand and the curse was repelled yet again; but Harry was mere feet away now and he could see Snape’s face clearly at last: He was no longer sneering or jeering; the blazing flames showed a face full of rage. Mustering all his powers of concentration, Harry thought, Levi —
“No, Potter!” [...] Snape’s pale face, illuminated by the flaming cabin, was suffused with hatred just as it had been before he had cursed Dumbledore.
“You dare use my own spells against me, Potter? It was I who invented them — I, the Half-Blood Prince! And you’d turn my inventions on me, like your filthy father, would you? I don’t think so . . . no!”