Tarecgosa is a member of the Blue Dragonflight in World of Warcraft, who sacrifices herself to expose the plot from Arygos and Deathwing in Cataclysm. In the end, Tarecgosa's essence is bound into a bough staff of the world tree and makes itself to Dragonwrath, Tarecgosa's Rest.
Dragonwrath, Tarecgosa's Rest is the best weapon on Patch 4.2.0. Although the Cataclysm has been the past and the staff attributes have been insignificant, this weapon is worth to win. Players could be transformed into Tarecgosa's Visage by the staff and free to fly in the sky. 
It appears a guiding quest automatically after killing a monster in the Firelands. Mage, Warlock, Druid, Priest and Shaman also can receive this quest. Then you can look for a variety of quest items by the guidance in Firelands and finally to defeat Ragnaros and get the Heart of Flame. It takes about ten weeks. Kalecgos will have a grand celebration in Stormwind/Orgrimmar and use the materials you gained to cast the Dragonwrath, Tarecgosa's Rest, that is legendary staff. However, the essence of the Tarecgosa will perch in the staff forever.
You and your guild will get the achievements of Dragonwrath, Tarecgosa's Rest after obtaining the legendary staff. Besides you can purchase the Lil' Tarecgosa from guild masters, that's a good bonus for us.

Dragonwrath, Tarecgosa's Rest