Yin Gu

Fang Yuan activates Yin Gu from the Yin Yang Rotation Gu pair and merges it into Bai Ning Bing’s ice sculpture when Northern Dark Ice Soul Physique is about to finish killing its host. Bai Ning Bing breaks free alive, no longer holding that ten extreme physique, at ninety percent aptitude instead of one hundred. ^{ch. 199}

The pair as a whole is covered on Yin Yang Rotation Gu. The remaining half is covered on Yang Gu.

Appearance

Yin Gu is the black worm of the Yin Yang Rotation Gu pair, and it revolves with a white one in an orbit that forms a light sphere. ^{ch. 199}

Effect

Yin Gu used on a male body turns yang into yin and makes the target a woman. Fang Yuan calls it a rank four healing Gu with the effect of bringing the dead to life. Using it lowers the Gu Master’s aptitude by ten percent. For a ten extreme physique that drop is not permanent: as cultivation continues, aptitude recovers toward the extreme again, and Yang Gu is then needed to turn the user around and cut aptitude by ten percent once more. ^{ch. 199} The Gu that saves Bai Ning Bing does not resurrect the Gu worms lost when those worms froze to death. ^{ch. 200}

Pair and feeding

Yin Yang Rotation Gu all come in pairs. After Yin Gu is used, only Yang Gu remains to reverse the change. ^{ch. 199} If Yin Gu and Yang Gu are intact and form a complete Taiji light sphere, they feed on the transformation of yin and yang qi and are self-sufficient. ^{ch. 202} The sealed pair was rank four when Problem Nipped in the Bud Gu pulled it from First gen Gu Yue, and Fang Yuan later seizes and refines it. ^{ch. 194 ch. 197}