Xixing Dafa in DOMD?

[Ren Wo Xing]

I was just reading Lu Ding Ji, and noticed that in the beginning of the book, Hai Dafu used a martial arts that was 'adhesive' (the false Empress wasn't able to pull away), and that drained away not only her internal energy, but also her very life force. That sounds incredibly similar to Ren Woxing's "Xixing Dafa", except that Hai Dafu didn't seem to gain anything from it. Does anyone know if it's explained later in the book, or if any hints are given as to that skill? As it seems pretty interesting/powerful.

[Laviathan]

This martial art only appeared in the part when Hai Dafu and Mao Dongzhu (fake empress dowager) fought. It was described as a skill developed by Hai Dafu himself to counter Mao Dongzhu's Bone-Dissolving Palm. It was called the "Yin Yang Grind". The theory is to generate two extreme opposite types of internal energy (Yin and Yang) in your body, and once connected with your opponent you can "grind" the opponent's internal power away. The skills is therefore not an absorbing art like Xixing Dafa or Beiming Shengong. The reason why Mao Dongzhu couldn't pull away was because she was caught in the middle of two opposing forces coming out of Hai Dafu's palms.