Find Islen Waterseer in the Barrens.
Long has it been since you were last tested, [player]. You have shown patience thus far in your studies, but the time has come for you to learn more. The time has come for you to learn about the purity of water.
Seek out Islen Waterseer in the Barrens. She is along the eastern coast, south of the Southfury River and Ratchet. You will find her there at her fishing hut. Good luck to you, [player].