Earlier he had used the moonlit fog of obscurity to call Meifeng, the purple flower spore sycamore tree friend he had made in his time in Deer Mountain Range.
As for why he decided to obscure himself before calling Meifeng, it was because of Meifeng's reaction which went exactly as he had expected it to, which was her talking his ear off with her complaining about how Yang Qing had been neglectful as a friend before she went off tangent and started bragging on how she could outsing the serenity river skylark.
It eventually turned into a competition as the duo decided to duel, with Yang Qing forced into the role of a judge. It was the first time he met a case he couldn't handle. He quickly used the case he had on hand as an excuse not to give his opinion on who was better between the two.