The so-called cauldron is actually about exchanging blows with an opponent, ensuring you aren't harmed, and then sensing that special power in his palm, transforming it into your own strength for enhancement.
This method is dangerous because if not handled carefully, it could cost you your life. However, it also offers constant opportunities; once you obtain this power, the enhancement is substantial.
Therefore, many who venture into the cauldron need precise prior knowledge, because being overwhelmed by the opponent due to carelessness could be embarrassing.
Liu Chen is confident because of the Green Lotus Sword Song. After mastering the Green Lotus Sword Qi, he found it truly remarkable.
