So Q'onzu, who are they?

[Amadis-draka (Amadis)]

@Gornur-nerzhul

Thrall says: The Horn of Cenarius!
Tyrande Whisperwind says: It has been too long since we fought side by side. As we did against Archimonde.
Lady Jaina Proudmoore says: But this tree shall not be sacrificed.

Gornur found where it was Tyrande and Thrall talked! I knew I remembered them doing so. It was during this quest here:

The Age of Mortals