Tonight we tried and 2 shot the Valithria encounter in 5:50 minutes on 25 man.
I was hoping that I would get to go into portals just for the sake of seeing how well I could do. I prepared with talents, glyphs and gear ahead in time much like Keeva recommended.
Unfortunately I dropped the buff stack in my last portal phase but according to the DPS Graph in World of Logs I was doing 53824 HPS just before that if that's truthful. I had nourish crits for 30k, Swiftmend crits for 40k and Rejuvenation ticking for 7k.
It's a very fun encounter! We used 3 paladins and this very tree for portals and we had 2 priests and a shaman raid heal. I ended up second on the meters but it's all about keeping the buff stack up, #1 never dropped it and #3 dropped it earlier than what I did.