There was a 'Tian Yuan Di Fang* Pavilion' on the 'Zhai Xing Tower**', locked up tightly behind layers of doors in peacetime. For the sake of this Tia Yuan Di Fang Pavilion, many masters of the Ling Shu Institute became bald. It would create a special optical network outside the Nine Gates and was very tightly knitted. Even at night, it would easily be covered by the light of stars, moon, and flames. Unless one had unusual abilities, it would hardly be visible to the naked eye.

*天圆地方, lit. Round Sky, Square Earth: an ancient traditional Chinese philosophy where people believed that the sky is a rounded dome and the ground is flat. This was also incorporated in their architecture.

** Star-plucking Tower, first mentioned in Chapter 22

This layer of optical network was 300 feet up from the ground and would not affect the people and animals on the ground. If someone flew by using the Eagle Armor, at low altitude, they would be discovered by the gate guards, there would be Baihong arrows waiting for them. If the Eagle flew above 300 feet, it would touch the anti-air net.

The light would then be reflected back to the Tian Yuan Di Fang Pavilion, then back to the covert piers in the area of the anti-air net through special mirrors. The piers would then move in accordance with the light signal and would lock on the position of the offender, shooting arrows from all directions. If the Eagle tried to dodge, they would soon find that in the scope of the anti-air net, where there were secret piers, arrows would continue to follow them inseparably like shadows.

Only on New Year's Eve, the Tian Yuan Di Fang Pavilion would temporarily close the anti-air net for its annual maintenance, and the task of keeping watch would be handed over to the guarding stations on the Red Kites.

"That path-finding Eagle will not be returning; the commander of the foreigners will soon remember the legendary anti-air net from the stories. Under the command of the Feng Huo Order, all Red Kites will go up to the sky, and the position of the anti-air net will change accordingly. For a while, they will not know where that mechanism had run to. The closer they approach the capital, the more afraid they will be to let the Eagle Armor fly too high...,” Gu Yun whispered to Tan Hong Fei, "Give orders, tell the brothers to rest well, we will start at night. The Black Eagle goes first, suppressing them from high places. Light Cavalry will ambush them from both wings, breaking up the enemy line. Do not be eager to fight, attack then leave, do not get yourselves trapped inside. The chariots will pretend to block their path, blowing up two or three rounds then letting them retreat. Do not force the other party to their last resort. Our troops are not strong enough."