The reason why Elder Du was so surprised to the point where he did something that was unlike him, was because when he probed the young man's cauldron with his soul energy, he sensed the pill forming and taking shape slowly.
That's right, the explosion earlier was not the indication of a refinement failure but the evidence of pill forming.
However, how could that be? Not to mention arriving at the last process by getting all the steps right, just trying to purify the ingredients and getting their essence, should have burned down all the ingredients due to the intensity of the flames.
However, to his surprise, the young man not only successfully extracted their essence, he even coagulated the liquid together and was now trying to form the pill.
