The Demon World, North Nether Mountain.
Deep within a cavern.
Dense spiritual energy filled the cavern, and bubbles rose in a pool at its center.
That spiritual energy emanated from the spirit liquid.
Such a sight was exceedingly rare in the Demon World.
Spiritual energy was scarce in the Demon World, making it extraordinarily difficult for cultivators to absorb it and cultivate here.
That was also why Wugou and Ning Ke had felt their cultivation stagnate after arriving in the Demon World.
Yet this pool consisted entirely of condensed spiritual energy, every drop exceptionally pure. Absorbing it all would easily raise one's cultivation by an entire major stage.
At that moment, a man sat deep within the pool, his eyes closed. Spiritual energy streamed into his pores, even forming a vortex behind him that poured endlessly into his body.
It was Lou Yunxiao.
During the battle in Northern Tour City, the Demonic Aura within him had already reached the peak of the Spirit Transformation Stage, but his spiritual energy had remained at the middle of that stage.
With the pool's help, his spiritual energy had caught up to his Demonic Aura in just ten days. He had now reached the final step of breaking through to Integration.
The vortex of spiritual energy spun faster and faster, churning the pool.
Outside North Nether Mountain, dark clouds gathered, arcs of lightning darting among them.
The transition from the Spirit Transformation Stage to Integration marked a qualitative leap in a cultivator's strength.
Only by enduring the tempering of a thunder tribulation could they advance.
But it also carried tremendous risk. A moment's carelessness could annihilate both mind and soul.
Lou Yunxiao frowned slightly and released a protective barrier woven from spiritual energy and Demonic Aura.
Once several layers surrounded him, the first Thunder