Ding Ling had mastered far too many secret techniques.
Especially at the Research Institute, he had obtained countless perfected secret techniques related to the application, refinement, and other aspects of the Curse Source.
At this moment, he used those techniques to help refine the Curse Source in the Origin Land. Refining the Curse Source Qi was extremely easy. After all, all of Ding Ling's secret techniques had reached max level, and he had mastered many such techniques. Refining these Curse Sources was as simple and natural to him as eating or drinking.
Simple and smooth as it was,
refining this vast amount of Curse Source and Curse Source Qi still required time.
Fortunately, Zhu Qingling herself was also extremely powerful.
And as they continued refining it along the way,
Zhu Qingling's strength continued to surge. This made their coordination increasingly seamless, and their refining efficiency kept rising.
Even so,
the refining still continued for a full seven days and seven nights.
During these days, Zhu Qingling also turned her attention to the human cities outside. She had already received Ding Ling's warning and knew that the Four Demon Kings had fled. She was worried that, driven into a corner, the Four Demon Kings might use the humans to threaten her, or simply go on a rampage before their deaths and slaughter all the humans.
If the Four Demon Kings joined forces, they absolutely possessed the strength to overturn humanity with ease.
However, unless they opened the Origin Land, the Four Demon Kings were generally at odds with one another. Stabbing each other in the back was commonplace.
That was precisely why humanity had been given time to catch its breath again and again.
Otherwise, humanity would have been wiped out long ago.
But now, would the Four Demon Kings attack