Seek out Alexstrasza the Life-Binder at Wyrmrest Temple in Dragonblight.
Our assault against Angrathar has staggered the Scourge, but they remain unrelenting. From overhead they send their frost wyrms to strafe the field of battle, making an advance upon the gate itself impossible. The frost wyrm attacks must be stopped, but before we defile the bones of ancient dragons, we must gain permission from their queen.
Travel southeast to Wyrmrest Temple and seek out Queen Alexstrasza. Tell her what we must do and ask her for guidance.
You have come seeking my council, mortal. This I know, but do you know what it is that you face?
<Alexstrasza points northward.>
North of here are the dying grounds of Galakrond - progenitor of dragonkind. It is from Galakrond that the Titans created the Aspects. Imagine, then, the power of Galakrond. His size alone was greater than all of the Aspects combined! Now attempt to understand what the Scourge do in the Great Dragonblight.
Frost wyrms, mortal, should be the least of your concerns.