Dumbledore stroked his beard and said slowly, "I can now roughly infer the plan of 'My Lord' and the Isaiah Society."
"'My Lord' and the Isaiah Society's plan?" Wizet's eyes flickered as he quickly followed Dumbledore's train of thought. "The Killing Curse?"
The Killing Curse was one of the most peculiar forms of magic he had encountered so far. Its most crucial characteristic was that it had no so-called counter-curse—or rather, no counter-charm.
Like the other two of the "Three Unforgivable Curses"—the Imperius Curse and the Cruciatus Curse—the Imperius Curse could be broken through willpower, while the Cruciatus Curse's counter-charm...
He and Snape had essentially invented one. Even torture by the Cruciatus Curse on the level suffered by Frank Longbottom and Alice Longbottom could be healed by the Soul Healing Technique.
He had actually tried researching the Killing Curse as well, hoping to find a counter-charm for it. However, his research had so far yielded only a theoretical conjecture.
That was, across the entire magical system, the priority of a Magical Contract should be higher than that of the Killing Curse, while the Killing Curse took priority over most magic.
He had arrived at this conjecture because of the Sacrificial Protection on Harry.
The so-called Sacrificial Protection was an extremely ancient form of magic with exceptionally harsh casting conditions: when someone could clearly escape, yet resolutely chose to die in order to protect another, they could cast this magic.
From the perspective of a Magical Contract, it meant using one's own life as the condition of the contract in order to protect its target.
Perhaps this conjecture could explain that question—why, after Voldemort cast the Killing Curse on Harry, who possessed Sacrificial Protection, that green light rebounded onto Voldemort himself.
"Yes!" Upon hearing Wizet mention this magic, Dumbledore