Watched the L2R 25 man video today:
https://www.youtube.com/watch?v=5eRanHhygCM
Healers will need to take buffs to manage the damage, there are three and they only are available once and come in this order:
Red (Gift of Life - 100% healing)
Green (Essence of Dreams - heal duplication/distribution to entire raid)
Blue (Source of Magic - 75% healing spell mana reduction, 100% spell haste)
Not sure what the best way to divide this is (and there probably isn't a "best" way). Speaking as a disc priest green is probably weakest for me because AFAIK the heal duplication doesn't duplicate my bubbles - and I'm all about the bubbles :) . I've also read this is healable by two so if we have enrage timer issues we can try that.
Anyway, looks like an interesting fight.