The 'Spirit Refinement Technique' is an extraordinary cultivation art even in the True Immortal Realm. It incorporates some laws of heaven and earth, and once successfully mastered, the spiritual sense would instantly receive an incredible boost.
The cultivation art was split up into three stages. Mastering the first stage could double one's spiritual sense, mastering the second stage could quadruple one's spiritual sense, and mastering the third stage could enhance one's spiritual sense by eightfold or even more.
The conditions necessary to cultivate this technique are extremely strict. Despite not having many conditions, and the minimum requirement of cultivation base was only the Deity Transformation Stage, but one of the prerequisites was that the person must have a body powerful enough and spiritual sense so that he could deal with the immense reaction of cultivation art.
If one's spiritual sense were to be multiplied by this cultivation art, but their body and spiritual sense weren't powerful enough to handle such a drastic boost, then they would instantly self-detonate and perish.
According to the guidelines stipulated by the cultivation art, one had to possess spiritual sense that was around twice as powerful as that of others at the same cultivation base if they wanted to cultivate the first stage. The requirements stipulated for one's physical body were even more diabolical; even the extreme outliers in terms of physical constitution would only just barely satisfy the outlined conditions.
It was extremely rare for anyone to be able to fulfill even one aspect of these two sets of conditions, and those who fulfilled both sets of conditions were virtually non-existent in the Spirit Realm.
After all, most cultivators either excelled in one aspect or another, or were far from satisfying the conditions in both areas.
As for the second and third stages, the requirements were even more insane. However, the second half of the art of cultivation offered a solution. This consisted of two pill recipes, one of which was known as the Body Fulfillment Pill, while the other was known as the Soul Condensing Pill.
According to the recipes, one of the pills could enhance one's spiritual sense while the other bolstered one's physical body. Consumption of those pills over a long period of time could slowly allow one to satisfy the conditions required to cultivate the Spirit Refinement Technique.
For the second stage, as long as one could master the first stage, the enhanced spiritual sense would probably be able to barely satisfy the conditions.
PS.: As for the third stage, the required conditions were not mentioned, but considering the previous stages, the user must have an even stronger body and a much more powerful spiritual sense.