Gift of the Gathering Storm

Gift of the Gathering Storm is the Cenarion Circle set for Shamans.

Source
Gift of the Gathering Storm can be acquired through quests given by Keyl Swiftclaw, Warden Haro and Windcaller Yessendra, who can all be found at Cenarion Hold in Silithus.

The quests require a given Reputation with the Cenarion Circle, and  (which drop from Trash Mobs in the Ruins of Ahn'Qiraj) and a token from a boss in the Ruins of Ahn'Qiraj.