The Cipher of Damnation quest chain

The Earthen Ring has sent representatives to the horde and alliance, seeking help communing with the spirits of Shadowmoon Valley, and healing the damage done to the valley. In the process, you discover how the land was shattered, and defeat an elemental lord.

This quest has several dialogs and a couple of cut scenes that explain details not found otherwise.

Rewards
Also, one of the following:

As well, several lesser items from the individual quests, including some tubers from Oronok's farm.