Kill any combination of 15 Dragonblight Mage Hunters, Moonrest Stalkers, Surge Needle Sorcerers, and Focus Wizards. After you have done that, return to Ethenial Moonshadow at Moonrest Gardens.
15x Blue Dragonflight forces at Moonrest Gardens slain
These so-called mage hunters came here and destroyed our resting place.
Avenge us, or I will see to it that your base of operations is overrun with the spirits of the dead!