To summon lightning bolts, one had to first possess a body strong enough to withstand the power of lightning. Generally, a lightning cultivator had to first go through the tempering of natural lightning bolts and obtain the ability to connect one's stars to the natural world before one could start summoning them.

Thus, reaching the King Realm and forming a certain degree of resonance with lightning were the minimum requirements. More often than not, many lightning cultivators would only be capable of this feat upon reaching late-stage King Realm. 

Just summoning and borrowing the power of one or two lightning bolts would be enough to greatly increase one's combat prowess. As for Xiang Shaoyun's feat of easily summoning 12 mutated...