How to finish the swamp in the dark?

First of all, the mission is in Moqiyang, Dawang Village, Death Marsh! He tells you a cold joke first, then asks you to visit others in the death swamp and find three cold jokes to complete the task. This is a 24-hour limited task.

The first two people are easy to find, both in Dawang Village. One is a swordsman, the other is Sima Yanzi, but the third one is hard to find. He has been looking for waves for nearly an hour.