Luo Chen's expression subtly changed.
The Nine Tribulations and Three Nirvana-nature are three realms within the "Heavenly Phoenix Nirvana Sutra" which he cultivated during the Golden Core Period.
They are Magic Power Nirvana, Physical Nirvana, and Divine Soul Nirvana.
Every Nirvana completed brings tremendous benefits to the cultivator.
He wasn't surprised that Youquan knew about these things, after all, it was Youquan who insisted he take up this cultivation technique to enhance his fire control and refine the Fourth Order Transformation Pill.
However, he was astonished that the other party could deduce that he had already completed the Second Nirvana simply from noticing how quickly he recovered his qi power.
Understanding is one thing, but to know so intricately without actually cultivating this technique was enough to make Luo Chen wary.
"Something's wrong!" Youquan suddenly spoke up, stopping in front of Luo Chen, staring intensely at his face.
