In Chapter 7 - The Power of the Night, you help Huln Highmountain track down and recruit two former Night Warriors - Khaliiq from Maldraxxus, and The Stonewright from Revendreth - to help with a ritual for Tyrande Whisperwind. Thankfully, the ritual is successful. Tyrande Whisperwind is saved from being overcome with the power of the Night Warrior, and you learn that Elune is the Winter Queen's sister. What's more, Elune leaves behind The Sisters' Tear, which becomes the new sigil of Ardenweald.
Shandris Feathermoon: Mother... Is it you?
Tyrande Whisperwind: I am myself again.
Shandris Feathermoon: What I have seen this day, I can scarcely believe.
Tyrande Whisperwind: I was present for every moment, and yet... outside myself. As much of a witness as you were.
Shandris Feathermoon: So much beauty in her voice. And sorrow as well. The tear...
Tyrande Whisperwind: Was much as mine as hers.
Shandris Feathermoon: The Winter Queen spoke of a purpose for the souls of our people. What did she mean?
Tyrande Whisperwind: That, Elune did not tell me, daughter. Not yet.