The Eighteen Needles of Returning to Life cannot kill directly, but they can indirectly, and the process is naturally a bit troublesome. To avoid arousing Fatigue Sect's suspicions, Luo Chao arranged for it to look like a car accident.
Yang He Ping would leave earlier than the people from the Fatigue Sect, so even if he suspected Luo Chao, he had no concrete evidence. However, the needle Luo Chao used on Yang He Ping had a unique effect: it erased a segment of his memory, making him forget that Luo Chao had pricked him. Nevertheless, the people from the Fatigue Sect possessed a unique Silver Needle Technique, and their mental awareness was stronger than the average person, making it impossible to erase their memory. Therefore, Luo Chao had to kill him.
