"Spot on," said Harry. "Ten points to Team Hermione. It was a very specific charm. My mum invented it. It meant that Riddle's harmful magic or intent couldn't ever really go to its full effect against me, and me alone. My mum used her death to power the spell. It's borderline necromancy, but I try not to think about that. It had to be clever enough to deceive Riddle ... to allow him to hurt me a little, but ultimately not be able to kill me with magic. He is arrogant, but very far from stupid. He would have worked it out if he'd known, so he had to be prevented from suspecting anything.