But so far, the Blood Magic was ancient and mystifying; it defied some of the most basic magic principles she had always believed to be true. It was more closely related to wandless magic. She could utilize it independently, as she had with McGonagall. But it belonged to both her and Malfoy, so it was likely stronger when they could use it together. And both of their intentions played a part; Malfoy seemed to suggest he would use it to kill. The magical suppression potion did not stop it just before.