Initiate Rainbow Bladework and fight using an illusory sword rain, while creating the maximum number of Rain Swords.
Rainbow Bladework
These effects carry over to other characters.
Puzzles, Secrets, and Hidden Chests in Dragonspine
Kazuha
Puzzles, Secrets, and Hidden Chests in Liyue
Hu Tao
Sayu
Shenhe
Ragged Records Hidden Quest Guide