Gu Shuangpu participated with other Nascent Soul cultivators in a meeting about the Moulan invasion. They were briefed by Enlightened Leaf Sect Master Wu Peng and the Flowing Mind Sect's Lady Qi. In the meeting on next day, the hosts were forced to agree to many conditions. The most important one being being that high grade assignments must be participated by an equal share of cultivators among the four powers.
Gu Shuangpu, Old man Ma from the Righteous Dao Alliance's Overwhelming Pavilion and Han Li led a party of eight Core Formation cultivators to the strategic location at the border of the State of Yu as support to Nine Nations Union's forces. They joined Senior Lu, Clear Void Sect's Chong Xuzi, Yellow Maple Valley's Murong Brothers and the Saber Transformation Dock's Li Yingzhu, who were a garrison there.
Soon after, Bu Yunhe retreating from Sky Terrace Valley joined them. Then Moulan spell warriors appeared. They decided one on one duel. Old man Ma fought Great Sage Ku Yao of Fire Rite Tribe. With Supreme Eight Trigram Diagram he was able to come to a draw against Ku Yao and his Fire Spirit Flood Dragon. As black-robed Heavenweep wanted to fight next, Han Li faced him. Using Divine Devilbane Lightning black demon Nascent was killed. Rest of the Moulan troops retreated. This was suprising for Senior Lu and others.
Afterwards, Gu Shuangpu visited Senior Lu. He wanted to convince him that Han Li was a spy for Moulan. When Senior Lu was handed a jade slip, it transformed into the Twintailed Jade Serpent, which killed him with its poison.  Then, it turned out this was just a flesh puppet and Daoist Gu was caught in a barrier. He admitted to Senior Lu, Han Li and Old man Ma that he was originally from the Moulan tribes. Han Li accidentally eavesdropped him during fight before. He agonized how he lived concealed in the Heavenly South for so long, yet he fell to such a careless mistake. When he was to be executed on spot, Gu Shuangpu used Spiritfuse Technique to fuse with his Twintailed Jade Serpent. He turned into half-man, half-demon serpent monster and its power increased to a mid Nascent Soul stage. As it broke the barrier, Han Li turned it into an ice sculpture with Celestial Ice Flames.