Ah good old Halfus Wyrmbreaker. This fight is very, very simple on enhance shammy for one reason: Shadow Nova. Thanks to our wind shear we can kick Every.Single.One. And we should! That's it, there's the fight!
Ok, ok, there is a bit more you can do.
- Unless Storm Rider comes out super-duper-immediately the first Shadow Nova will still be a fast cast. We have all our melee count to 4 or 5 and then start kicking and it catches the cast about 90% of the time. In the beginning I didn't go for this first kick in fear of screwing up my wind shear cool down, but once you've done the fight a few times you get a sense for the timing of the first cast and you can kick as well.
- It's important that the first kick does land, especially if your guild is new to heorics as the tanks may not be able to survive a nova + damage from the drakes/whelps.
As long as you are getting Every.Single.Kick. and pushing your dps as much as possible around it, this fight should go quickly. Make sure you've got Deadly Boss Mod warnings for Shadow Nova turned on - but don't rely on the sound alone as it can sometimes lag behind.