Why Can Hogwarts Detect Fire but Not the Killing Curse?

Kane stared at Voldemort in confusion, still wanting to put up one last stubborn front. "Uh, what do you mean by my handiwork?"

Voldemort looked at Kane, who was still playing dumb even now, and could not help nodding. Refusing to give up even the slightest chance of survival until the very end could barely be considered a virtue.

"I admire you, Kane, but you still cannot deceive me... after all, I heard this from Hagrid himself. You are probably the only one in Hogwarts capable of creating these tentacles," Voldemort said darkly.

"I never put on a show like this in front of Hagrid." Kane still shook his head. Honestly, he was more inclined to believe that Dumbledore had used various means to let Voldemort know about it in order to speed up the dungeon's progress.

But Voldemort's next words cleared Dumbledore of suspicion. "Yes, Hagrid did not know before, but Ron Weasley did. You know, Mr. Weasley values your friendship greatly. Bragging to others about his friends is what he enjoys doing most."

...Fine, that made sense." Kane pulled a long face and walked helplessly toward Voldemort.

"I thought you would find a way through this thing yourself?" he said darkly.

"Bringing you here was one of the ways I thought of." As Voldemort spoke, he patted Kane on the shoulder and urged, "Begin, Kane. Let me see."

"Mm-hm." Kane answered casually, and the tentacles beneath the trapdoor, which had been baring their fangs and claws, abruptly became docile. Like seaweed drifting with the waves beneath the ocean, they eventually wove themselves into a staircase leading downward.

"I think we should go down together, shouldn't we, Kane?" Voldemort said, extending a hand toward him.

"You are quite cautious, Professor."

Kane took Voldemort's hand and walked down on his