The armored cavalry（装甲部队） deployed by Huyan Zhuo could not be destroyed unless barbed lances（长矛） were used. Tang Long presented a drawing of such a lance and lance could be made according to the drawing. However no one was able to use them. Tang Long suggested: "My cousin Xu Ning, an arms instructor in the capital, knows how to use barbed lances. The art has been handed down from generation to generation. We can bring him to the mountain." Everyone began to thing how to lure Xu Ning to the mountain. Tang Long had a plan: "Xu Ning has a suit of goose-feather armor hopped in metal. It is a matchless ancestral treasure. Xu Ning cherishes it like his life. He keeps it in a leather box that hangs from the central beam in his bedroom. If we can get hold of that armor, he'll have to come here whether he wants to or not." Then he whispered his stratagem（策略，计谋） to Song Jiang. Military councilor Wu Ying sent Shi Qian to attend to this matter. Shi Qian, whose body was light as a swallow, excelled at（突出，擅长） leaping onto roofs and vaulting over walls. Soon he arrive in the capital. Shi Qian inquired of Xu Ning's residence, studied the surrounding area and located where the metal-bound goose feather armor was placed. Finally, he learnt that Xu Ning would be on guard duty the next day at the fifth watch. At the fifth watch, Shi Qian stole into the kitchen when Xu Ning was having something to eat. As soon as Xu Ning had lift, Shi Qian went upstairs to Xu Ning's bedroom. Xu Ning's wife, who heard sounds coming from the beam, asked her maid what it was. Shi Qian promptly squeaked like a rat. Thinking that it was only rats fighting, Xu Ning's wife went to sleep. Seizing this opportunity, Shi Qian snatched the armor. Xu Ning returned home and heard that his metal-bound goose feather armor had been stolen. Guided by Tang Long, Xu Ning ran after Shi Qian and ended up at Liangshan Marsh. Convinced by the gathered leaders, Xu Ning joined the forces in the stronghold. Later Xu Ning destroyed Huyan Zhou's armored cavalry with his barbed lances.