Sacrifice
Song Yan only thought that the blood tree did not grow a fruit yet but now that she saw Hu Shan's condition, she was quite sure that the blood tree which was being raised by the two Chen sisters had indeed grown fruit and that fruit was now being used to create venom to transform good and healthy looking people into zombie vampires.
The last time when she met the zombie vampire when she was dealing with Wu Genji's case, she thought that it was being used by a dark cultivator as a familiar but now she had a very good idea what and why that Zombie vampire was being raised by someone.