To sense lightning what he needed to focus on was the surroundings.
He was currently in an underground hall - there couldn't be the worst possible place to try to sense the lightning element.
But there was no choice for Ye Tian Yun, he couldn't go out for the next one month, and if he did go, he wouldn't be able to get back here.
It wasn't worth it, because stabilizing his Sword Domain wasn't his only goal. He had one more thing to do.
And to achieve both of these goals, this was the best place to cultivate for Ye Tian Yun.
Due to the already existing arrays, no one outside the hall can know what's going on; and what and how Ye Tian Yun was cultivating and making use of his time inside this hall.
Thus, Ye Tian Yun had to try and focus on the lightning element through his surroundings.
With a clear-headed mind, Ye Tian Yun focused on the very basics of what is needed to create lightning through his surroundings.
