The chambers at the bottom of the tower were scorching hot, and the spiritual energy in them was incredibly dense, so much so that you could sense it with your eyes closed. This was what martial practitioners required for their cultivation.
Whether it was ordinary martial practitioners or someone like Chen Feng, they all had a great need for spiritual energy.
The former would use this spiritual energy to transform it into Qi, while the latter used it to nourish their physical bodies and convert it into Vital Essence.
It could be said that the spiritual energy of heaven and earth was the foundation of martial cultivation. In the most excellent cultivation places in the most powerful martial traditions, like the eight great martial academies revered as holy places by the warriors of Tianhuang City, there were incredibly powerful cultivation places with incredibly rich spiritual energy. Cultivating within them made their efforts twice as effective.