The lightning spell Five Thunders Smite the Crown was profoundly abstruse. Chen Lin studied it for a long time before finding his way into its mysteries. To fully assimilate it and reach the point where he could cast it would likely require another stretch of arduous cultivation.
The restrictions on casting it were considerable as well. It required both the five elemental spiritual roots and a lightning spiritual root, because the five thunders of Five Thunders Smite the Crown were the thunders of metal, wood, water, fire, and earth. Not one could be missing.
He had a metal-wood-water-fire quad-spiritual root and had later developed a lightning spiritual root, but he still lacked an earth spiritual root, so he could not practice it.
Fortunately, the inheritance provided a remedy: a treasure of the corresponding attribute could replace the missing spiritual root. However, this would greatly diminish the lightning spell's power, and the treasure replacing the spiritual root had to be of a sufficiently high grade.
After learning of this restriction, Chen Lin began considering a solution.
The best approach would naturally be to grow an earth spiritual root, just as he had grown his lightning spiritual root.
But secret arts for growing spiritual roots were exceedingly rare, and an earth spiritual root was not some high-grade spiritual root. No one would specially develop a secret method just for one.
As for creating such a method himself, he did not yet have that ability.
Growing a new spiritual root was therefore unrealistic. He could only search for earth-attribute treasures.
He immediately sent messages to Lu Youcai and Tian Haifu, asking them to purchase earth-attribute treasures-the higher their grade, the better. The grade of the treasure replacing the spiritual root directly determined the lightning spell's upper limit of power. This was no place