Chen Han went to the Library Pavilion to check some relevant Daoist Books.
According to records, Rootless Water is not limited to rainwater, apparently dew is also Rootless Water.
If it's dew, you can go to a higher location on the mountain, dew should be found, it doesn't necessarily need to be a rainy day.
However, you have to go up the mountain early in the morning; there's no way dew will be available at this time.
So, he decided to prepare other things first, and then try painting the Blessing and Peace Talisman.
Talisman pen and Yellow Paper, Cinnabar and such things are not hard to find; after all, the Demon-Vanquishing Celestial Venerable Hall has them stocked year-round. He directly asked his aunt for some, then returned to the courtyard and took out the vermillion inkstone.
