Dumbledore stroked his beard and said slowly, "I can already infer the general outline of The Master's and the Isaiah Society's plan."
"The Master's and the Isaiah Society's plan?" Vizet's eyes flickered, and he quickly followed Dumbledore's train of thought. "The Killing Curse?"
The Killing Curse was one of the strangest pieces of magic he had encountered so far. The key point was that this magic had no so-called counter-curse—or rather, no Counter-Curse.
Of the other two Unforgivable Curses—the Imperius Curse and the Cruciatus Curse—the Imperius Curse could be broken free from through willpower, while the Counter-Curse for the Cruciatus Curse...
He and Snape could be considered to have invented it. Even someone who had suffered torture from the Cruciatus Curse to the extent of Frank Longbottom and Alice Longbottom could be healed by the Soul Healing Art.
In truth, he had also tried studying the Killing Curse, wanting to find its Counter-Curse, but his research so far had only produced a theoretical conjecture.
That was, across the entire system of magic, the priority of a Magic Contract should be higher than that of the Killing Curse, while the priority of the Killing Curse stood above most magic.
The reason he had made this conjecture came from Love's Magic Protection on Harry.
So-called Love's Magic Protection was an extremely ancient magic, and the conditions for casting it were very harsh: when someone clearly had the chance to escape, yet resolved to die in order to protect another, that magic could be cast.
If viewed from the perspective of a Magic Contract, this was using one's own life as the contract condition in order to protect one's contract target.
Perhaps this conjecture could explain that question—after Voldemort cast the Killing Curse on Harry, who possessed Love's Magic Protection, why that