We actually one shot the Faction Champions this week but it took us six tries on the Twin Val'kyr to get them down.
Just keep an eye on your attunement and stay relatively close to the other colored portal if you need to change before an explosion. I was somewhere in the middle in range of both tanks for most of the fight, a bit closer to the dark twin. When healing the dark side I had the dark attunement as I then could absorb the dark orbs so that less people got hurt by them on my side. It worked pretty well.
When we got to Ulduar Ignis was kind enough to drop the last fragment I needed so now I've started the quest to finish the mace in the Yogg +3 fight.
I also have some conversations to share.
Sudden confession in the guild:
[Priest] I'm listening to Shania Twain and singing along and didn't realise
[Priest] I'm a bad person
[Priest] no u
Excerpt from the Northrend Beasts strategy recap:
[Warlock] What are the little fuckers called?
[Rogue] Don't set yourself up like that