Cain did not waste a second before circulating his Fiend Devourer Cultivation Technique to handle the sudden rush of energy that flooded his entire body. He was doing his best, but there was simply too much energy, and he could not use it fast enough.
It made sense that Cain would face such a problem. After all, the Dragon Blood Grass was a cultivation resource meant for Level 7 Wave Warriors. Those were individuals with much higher energy consumption than someone at Level 2.
If Cain did not do something fast, a significant amount of the energy flooding his body would begin to disperse. That was something he could not accept.
Using the Blood Refinement Art could help Cain handle that excess energy, but he was already focusing all his mental capacities on the Fiend Devourer Cultivation Technique.
