The Myriad Demon Sea.
Inside the Returning Abyss Secret Realm.
Lin Fei shuddered, and the nine cave heavens within him rumbled.
The spatial barriers of each cave heaven expanded again, as though heaven and earth were being created anew.
His main cave heaven expanded continuously from a diameter of one hundred and fifty kilometers, finally reaching roughly three hundred kilometers.
The other eight subsidiary cave heavens expanded as well, approaching three hundred kilometers in diameter.
Each cave heaven contained a vast ocean of magical power.
The slightest activation of the cave heavens would stir up towering waves, sending magical power surging.
"I've broken through to the Late Void Insight Realm!"
"It's only been six years..."
Lin Fei opened his eyes, his face brimming with smiles.
Ever since he had successfully refined that Human Immortal-level mechanical puppet, he had felt that he could break through at any moment.
In just six short years, it had happened as naturally as water flowing into a channel.
"For an ordinary Void Insight Realm cultivator, advancing from the early stage to the late stage takes at least three to five thousand years of cultivation."
"Cultivating with immortal crystals has greatly shortened that time. But reaching the perfect Void Insight Realm will still take more than a thousand years."
His method of cultivating nine cave heavens was certainly powerful.
But cultivating it also consumed tremendous resources and time.
Without those hundred thousand immortal crystals as cultivation resources, Lin Fei would probably have cultivated even more slowly than ordinary Void Insight Realm cultivators if he had relied solely on absorbing spiritual energy from heaven and earth and converting it into magical power.
Even with numerous spirit veins and immortal-grade spirit pills to assist him, his cultivation would not have progressed as quickly as it did by refining