A tough one :)

The best order I've found is Fire / Arcane / Earth / Shadow.
Feng must never cast Draw Flame, so nuke him as hard as you can right at the beginning. Arcane phase should not last very long too, and after that it's just kiting and survival.

Patch 6.1.2, 697 ilvl

Music : Lensko - Cetus
https://soundcloud.com/nocopyrightsounds/lensko-cetus-ncs-release

Armory : http://eu.battle.net/wow/en/character/hyjal/Araitik/advanced

Enjoy :)