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The higher level spiritual energy here is close to Immortal Qi, superior to that of the Soul-Cultivating Furnace and the Body-Cultivating Furnace.
According to Yin Ling, it would take only three hundred years to breed a lower grade imperial dragon vein, and a thousand years to breed a middle grade imperial dragon vein, with the highest being just a middle grade imperial dragon vein.
Additionally, as long as there is sufficient higher level Spirit Source, the Life-Prolonging Furnace can create powerful followers, like the Five Directions Mystical Beasts, the strongest of which can be at the peak of Quasi Emperor; this requires consuming a vast amount of Spirit Source and can be maintained for five.
Second, after undergoing the baptism of the Life-Prolonging Furnace, the recipient's cultivation talent can be enhanced by one grade, with the maximum enhancement being up to first grade, and their comprehension abilities will also improve significantly.
