From what I remember, he went to some kind of lightning place in the ocean, and defeated/killed the people there that was looking for enlightenment from the dao of lightning, then he took the dao of lightning with him. That's really all I that I remember. If I can get the chapter this was on that would be a bonus. Thanks!
It might be Immortal and Martial Dual Cultivation, but I can't remember if it is actually that or not
Hmm sounds like IMDC Chapter 857 where he subdued the Thunder Emperor's will of lightning but the chapter when he defeated the people there is 541 If you're very far into the novel Spoiler In 1445 he obtains the Divine Lightning in the Misleading Fog Lake
omg thanks so much! I was trying to find the chapter but I really couldn't. You saved me quite a bit of time with that