C53 Two Bamboo Slips

Inside this magical small bag were two bamboo slips that had already become a bit moldy. One of the bamboo slips had the "Heavenly Passage Technique" written on it while the other one had the "Pill Tao Arts" written on it.

What is this?

Judging from the words on the bamboo block, the second book seemed to be a Daoist alchemy book. Those old Daoist noses loved to mess around with this