Certain martial arts are the "black stars" of other martial arts: they just particularly stymie another technique. For example, the combination of Sin Tin Gung and 1 Yeung Finger Technique renders Ha Mo Gung ineffective, Ancient Tomb Sect techniques render Cheun Jen Sect martial arts ineffective, and the 9 Yum Jen Ging can counteract Ancient Tomb Sect techniques, etc.
Is Hong Lung 18 Palms depicted as a "black star" for the 9 Yum White Bone Claws? Maybe it's just the fact that Mui Chiu Fung suffered her first defeat in LOCH at Gwok Jing's hands when he used Hong Lung 18 Palms on her, but it seems to me that Hong Lung 18 Palms is 9 Yum White Bone Claws' "black star."