The Legend of Qin - Season 2 Episode 4 An Endangered City in A Long Night

Yue-er is about to recover Tianming when the spell begins to counterattack and poison herself. Gongshu Chou claims he has found out the fatal weak point of the Machinery City. Duanmu Rong arrives in time and saves Yue-er and Tianming. Wei Zhuang gives a tiny bottle of poison to his spy, who disguises himself as Duanmu Rong and deceives Gao Jianli who guards the Centre Pool. Master Xun sees Ge Nie doing something to the pool and is wounded. In fact, that man is the Wei Zhuang's assasin, Heiqilin(Black Kilin). He has disuised himself as the Mohist who run for help and entered the City. He puts the poison into the water which flows everywhere and gives power to the whole city. Gao Jianli tries to kill Ge Nie but Duanmu Rong stops him.