"No," he said slowly. "I will hex you, randomly and when you least expect it, which means that you will always have to be prepared and on your guard. I'm not doing those stupid scripted duels. Those are for Hufflepuffs."
He rested his arms on the desk and leaned forward. "You can prepare your essay and you can tell your parents to hex you." Something they should have done since she was old enough. A little dose of Cruciatus was more than enough to show the importance of defence. "You should become paranoid to the extreme. You should learn to check your books, clothes, make-up, shoes, bags routinely. You should learn to check your food, your drinks and your snacks. You should learn never to touch anything without testing it for hexes. You should tell all of that to your house mates, because I will make sure that you learn in the next few months everything your parents should have taught you instead of turning you into this sorry excuse of a Slytherin. In short, I will make your life hell so when you get out there, you might have an infinitesimal chance of surviving."