Those threads were not truly invisible, only exceedingly fine, like the mosquitoes in the Demon-Suppressing Prison. Even Jing Jiu would have struggled to notice them without looking carefully with his Sword Eye.
These threads were not an active means of attack, so naturally they bore no killing intent or hostility. They merely waited for their target to run into them.
Just as he had done when killing Snow Nation Monsters on the snowfield many years ago.
The question was, what kind of thread could be so fine, so sharp that even his skin felt a faint sting?
Another question was, with threads this sharp, how were their ends secured?
As a sword cultivator, he naturally understood that the finer something was, the sharper it became. The problem was that finer things were also more fragile, unless their internal binding forces were extraordinarily powerful.
Countless pieces of information flowed through his consciousness like water.
There were relevant physics papers, a very famous novel, and the gray sky curtain in the deepest part of the Sacrificial Hall.
He looked into the depths of the night, sensed dozens of extremely faint fluctuations in aura, and finally reached a conclusion.
These threads and that gray curtain were made of the same material-ultramicro particles material.
Ultramicro particles material referred to material composed of ultramicro particles as its basic units. Different fabrication methods gave it different physical properties.
Space stations, Military Mecha, and space elevators all frequently used this material.
Developed to its utmost potential, this material could naturally be used to kill, and with a certain classical beauty.
Someone had surrounded the Sacrificial Hall with ultramicro particles material threads.
But as Ran Handong had said, he would be safe as long as he did not leave the Sacrificial Hall. Why had the other party known