The process of subduing the Rainbow Core Flame was similar to the Vientiane Spiritual Flame.
Huang Yueli practically didn't spend much effort and subdued the deviant flame as she joyously started to check on it.
Rainbow Core Flame was a Water attribute deviant flame and was useful in uplifting the success rate of the medicinal herb to form into a pill. Which was to say that under the same situation of using same levelled ingredients, using the Rainbow Core Flame to refine pills would possibly refine a few more pieces of pills out.
But doing that also had its risks and the price of increasing the number of pills also raises the possibility of the failure of the pills.