"Vitality?"
"Right, for example, the spring thunder during Jingzhe can stimulate the growth of Spirit Plants," Yan Wushuang explained. "But for us to use Thunder Skill to replicate this spring thunder, we are completely clueless—the spells in the Sealing God Book also seem to be of little use."
...
Zheng Fa suddenly remembered the problem of modern cultivation of Spirit Plants—Mrs. Tian said it lacked a certain environment, if what Yan Wushuang said was true.
So, does this environment seem to be related to some kind of Heavenly Thunder?
The evidence for this speculation is rather weak, making it hard for Zheng Fa to be certain of its truth.
But Yan Wushuang stated it with certainty, raising Zheng Fa's interest in the Heavenly Stele.
