C1768 Resurgence of dead ash

How could this be?

Black Turtle picked up a corpse to check its wound, but was surprised to find out that there were no wounds at all. There weren't even any signs of being poisoned. How did they die?

Leng Yue, who was standing beside Black Tortoise, was also astonished. What kind of power could annihilate all of them without even making a sound? They only heard a weird cry