The Wen Dou has three parts, namely identifying materials, purification, and guessing the pill quality!
Identifying materials, as the name suggests, is about identifying alchemy materials. The contestants will respectively draw the more obscure alchemy materials they know or describe their key features for the opponent to recognize. This is a basic test of an alchemist's range and depth of knowledge in identifying alchemy materials.
Purification, also self-explanatory. Among the alchemy materials is one called 'Bitter Leaf Dragon Horn Root', which is extremely difficult to purify, almost comparable to some ancient Holy Medicine, making it a headache for alchemists. However, this material is plentiful and found everywhere.
So later on, in Wen Dou, 'purification' gradually evolved into using this material as the standard for practical assessment! Whoever can purify the Bitter Leaf Dragon Horn Root the best wins.
