It’s one of the things Lupin had worked with him on because he was good at charms and good with detail. Draco closes his eyes and takes himself through the procedure step-by-step before he gets out his wand. There’s no room for error. "I’m setting it for midnight tomorrow," he says, "and you’re taking Pansy with you. Do you still have the letter from your father that said he was going to try to contract you to Pansy?"