West Poison Au Yeung Fung's snake venom was probably the most potent poison in all of wuxia. We saw just how potent it was when it killed Yeung Hong in LOCH. Within minutes of exposure, Yeung Hong was not only dead, but his flesh began to disintegrate, and even the crows that fed on his decaying flesh perished. Hundreds of years later, this poison would be used by Wai Siu Bo as a corpse-dissolving acid...completely obliterating any trace of bone or flesh it came into contact with. That's potent stuff.
Sometimes, that is. Despite the poison's dramatic effect on Yeung Hong, it seemed less effective against several other characters.
North Beggar Hung 7 Gung was bitten by two of Au Yeung Fung's snakes during their struggle on the Au Yeungs' yacht. The poison opened up Hung 7 Gung's defenses and allowed Au Yeung Fung to land a blow on Hung 7 Gung that neutralized the great old beggar's martial arts for the next two years (and would have been neutralized forever had Hung 7 Gung not later gained the main inner power generating portion of the 9 Yum Jen Ging from South Emperor 1 Deng via Gwok Jing). Hung 7 Gung's ability to survive the poison we can probably attribute to his Greats-level inner power, but what about Gong Nam Freak # 4, Nam Hei Yan?
Nam Hei Yan was fatally bitten on the tongue by one of Au Yeung Fung's snakes on Peach Blossom Island. Nam Hei Yan did eventually die from the poison, but not until days or more likely, weeks later. Nam Hei Yan was no Great. The Gong Nam 7 Freaks were not devoid of inner power, but none of them had the kind of great inner power that I imagine would be required to resist Au Yeung Fung's snake poison. It was the poison from Nam Hei Yan's body that killed Yeung Hong, but the effects on the two victims were completely different: Nam Hei Yan managed to survive for weeks, while Yeung Hong began disintegrating in minutes. This is an inconsistency that is difficult to explain, because Nam Hei Yan did not have any poison resistance or superior inner power to resist it any better than Yeung Hong did.