There should still be a treasure vault beneath Funnel Lake. Even if there wasn't, there had to be something that gathered immortal energy. Otherwise, Funnel Lake could never have gathered such powerful immortal energy on its own and formed immortal spirit energy.
The Demon Cultivator craftsmen who designed and built the floating island over the sea had shown extraordinary ingenuity. They had shaped the lake in the center of the island like a funnel, allowing it to gather the surrounding immortal energy. As long as the floating island was moved to a place where immortal energy was present, it could absorb that energy and form an immortal-energy vortex, eventually raising its level. The stone doors beneath it should have led to the former abodes of some high-level cultivators on the island, or perhaps palaces that only the imperial family could enter. They had occupied the floating island's finest resources, so cultivating there had naturally been twice as effective, allowing them to advance much faster than the ordinary cultivators living by the lake.
"It seems what you said is true. You act swiftly, and you understand the language of the Nine Provinces. This place has already become a ruin, and people like me might suddenly arrive at any moment. With good luck^novel], you could still escape disaster. With bad luck, as now, you might fail to conceal your aura and expose yourself, and then you could very well perish here. There is no guarantee of safety. Your companions who fell into demonic cultivation are all dead now, and the barrier is gone. How will you reach the Spirit Transformation realm, let alone transform into the human form that is about to come? So I am giving you two choices. First, follow me from now on. I will give you cultivation pills