Cassie Kelpie and the Water Sprites

Cassie Kelpie and the Water Sprites was a band formed by Cassie and the Water Sprites. They had one known concert, known as Water Music.

History
It was unclear of the band was an actual entity or formed purely to trick the town of Ponyville. During the Water Music concert, Cassie used her hypnotic powers to hypnotize the town into destroying the Ponyville dam to help her Water Sprite friends.