Ying Yang gu

Two peculiar Gu Worms were circling and chasing each other within this light sphere. As the Taiji light sphere continued to rotate, they seemed to carry traces of great dao

Yin Gu or Yang Gu of Yin Yang Rotation Gu, this Gu can change (Yang to Yin) or (Yin to Yang) and give a person complete transformation. It is a Rank four healing Gu and has the effect of bringing the dead to life.

It has a weak point though, and that is the Gu Master’s aptitude will be lowered by 10% once it is used.

Other than that, it completely change person gender. Yin Yang Rotation Gu - Yin Gu is used in male body, to turn Yang into Yin, and become a woman. Yang Gu is used in female body, to turn Yin to Yang, and become a man.

etc.
For someone who have Ten Extreme Physique, they can use this Gu to change thier aptitude 100% to 90%. no more risking in having Ten Extreme Physique.

Interesting fact Bei Ning bing used this gu to turinto woman wehn using it. making him more beutiful but also weeker. It take away power from aperture and made her only ninty % strong. but not for long, secret, it is ten extreme physique wich explode when to strong like one hundered %. But because bei ning Bing used it she did not die when exploding.