The so-called Nether River referred to the human spine.
It began at the Wei Lü acupoint at the tailbone and traveled all the way upward.
Passing through the Gate of Life, Spine Clamp, Jade Pillow... it surged straight into the Niwan Palace at the crown of the head.
At this stage, the abundant Five Qi within the body would gradually grow restless and repellent, clashing with the newly formed Nether River.
Without any surprises, the meridians along the spine would send forth needle-pricking pain. Chilling yin energy would spread along the vertebrae, and the limbs and bones would swiftly turn cold.
Moreover, the soul would feel slightly faint.
However, this was a normal reaction from the soul's first contact with Netherworld Realm power.
Yet the longer one cultivated, the more negative symptoms and reactions would emerge.
The entire body would stiffen with cold as though one had fallen into an ice cave, while a layer of black qi covered the whole person.
The face would turn pale, and even the breath would carry a trace of icy yin chill, making one utterly unlike one's former self.
Then came the second step of cultivation: drawing in baleful intent and absorbing baleful intent.
At this stage, there were two choices. One could either travel far to perilous lands steeped in yin balefulness and search for baleful intent.
Or one could use the baleful intent leaking from the Corpse King Sword as a natural baleful seed, agitate the qi and blood on the spot, and draw that strand of pitch-black baleful intent down into the qi sea.
But one had to remember that baleful intent was not spiritual qi, nor was it vitality.
It was an incomparably yin, incomparably cold, vicious energy that specialized in devouring souls.
The moment it entered the qi