Ye Fan's tactical choice was very on-point. Instead of letting the numerous centipedes scurry about, he decided it was better to block their nest and use the Pill Fire to burn them alive within it. Burning them outside with the Pill Fire would have been difficult due to the vast space and the large number of centipedes—inevitably, some would escape.
For Ye Fan, these centipedes lacked lethality, but for others, it was definitely not the case, the key issue being the intense poison they harbored which had been strengthened through the nurturing and sealing by a master using secret techniques.
