Celestial Blessings

Jade Temple: Range DPS
Red Crane: Healers
White Tiger: Melee DPS
Black Ox: Tanks

You must choose one of those depending on your class and spec to complete the quest.

Yu'lon easy mode (ranged dps)
do this, and you'll love me after :)

- When you engage Wrathion just focus on avoiding damage in the begining, dont use your cd's instantly. When adds spawn, run out to the balcony ASAP but before that use and ability that lets you drop aggro (for mages invisibility, priests fade, etc)
Now the best part comes: adds will now go back to the center of the room with the gong. You will never see them again and won't have to worry about them :))

- Now's time to hurt Wrathion, just keep in mind that you never leave the balcony and don't go too close to the stairs or the adds will start chasing you again. So, avoid damage and do some dps.

- At some point (25% health) Wrathion will go back to the gong room to summon his mirror images. DONT FOLLOW, stay where you are, and heal yourself (glyphed invo for mages)

- After while all mirror images will drop dead, Wrathion will come back, so again: avoid damage and do your dps (just dont go near stairs)

If Wrathion goes again to summon his mirror image (that happens if you are like me lfr geared), again you stay there on balcony, heal, and dps him when he comes back.

As a heads up, because this conufused me:

For most of the celestials you just run up to where they're hanging out and get credit for talking to them; you don't even have to sit through the conversation.

For Yu'lon (Jade Serpent,) however, you have to talk to Wration out by the bridge heading in to the temple grounds, and then you'll be cutscene-ported to her room. If you go directly there you'll just see him hanging out with her doing nothing and the objective won't trigger.