The flood dragon came back because it smelt the snow lotus. A snow lotus wasn't only helpful for cultivators, it was also useful for monsters and ghosts. The flood dragon was quite excited, but unfortunately it lost the snow lotus.
The flood dragon lost the hint of the snow lotus, not because he moved slower than it, but because the snow lotus was tiny in its eyes. The flood dragon was too large so it was very easy for the snow lotus to hide from the flood dragon.
The snow lotus quickly ran into a gap between rocks, and the flood dragon couldn't do anything about it. Besides, the flood dragon didn't want to make loud noises in case Leng Shaoting was interrupted.
Luckily, as long as the distance between them was shorter than 10 meters, the flood dragon could still smell the snow lotus and followed it up here.
