Cloud Serpents are Epic vanity mounts that were added in Mists of Pandaria. Using cloud serpent mounts originally required the 
[Cloud Serpent Riding] skill, which was rewarded after completing 
[10-35] Riding the Skies at exalted reputation with the Order of the Cloud Serpent reputation faction at the Arboretum in Jade Forest. In Patch 6.0.2 the riding skill was removed, making them just like any other flying mount.
Vendor
Exalted with Order of the Cloud Serpent:
[Reins of the Azure Cloud Serpent] - 3000- [Reins of the Jade Cloud Serpent] - 3000
- [Reins of the Golden Cloud Serpent] - 3000
Exalted with August Celestials:
- [Yu'lei, Daughter of Jade] is purchased for 5,000 from Mistweaver Xia on the Timeless Isle.
Azure Cloud Serpent
Jade Cloud Serpent
Golden Cloud Serpent
Thundering August Cloud Serpent
Heavenly Golden Cloud Serpent
Yu'lei, Daughter of Jade
Drops
- [Reins of the Astral Cloud Serpent] - Rare drop from Elegon in the Mogu'shan Vaults
- [Reins of the Heavenly Onyx Cloud Serpent] - Rare drop from the Sha of Anger in Kun-Lai Summit
- [Reins of the Thundering Cobalt Cloud Serpent] - Rare drop from Nalak on the Isle of Thunder
- [Reins of the Thundering Ruby Cloud Serpent] - Guaranteed drop from Alani in the Vale of Eternal Blossoms
- [Reins of the Thundering Onyx Cloud Serpent] - Fairly rare drop from Huolon on the Timeless Isle
Astral Cloud Serpent
Heavenly Onyx Cloud Serpent
Thundering Cobalt Cloud Serpent
Thundering Ruby Cloud Serpent
Thundering Onyx Cloud Serpent
Achievement mounts
- [Reins of the Crimson Cloud Serpent] - [Glory of the Pandaria Hero]
- [Reins of the Heavenly Crimson Cloud Serpent] - [Glory of the Pandaria Raider]
- [Reins of the Thundering Jade Cloud Serpent] - [Guild Glory of the Pandaria Raider]
- [Reins of the Heavenly Azure Cloud Serpent] - [Lord of the Reins]
Crimson Cloud Serpent
Heavenly Crimson Cloud Serpent
Thundering Jade Cloud Serpent
Heavenly Azure Cloud Serpent
Quest reward
Onyx Cloud Serpent
| ||||||||||||||||||||||||||||||||||||||||||||
