shaman + druid is a good combo btw, and paladin/disc is good against iron prisons.
Keep efflorence up
Keep rejuv up at the other healer and you at all times
Regrowth when it's needed and with procs.
rotate cd's iron bark and barkskin when 11 seconds left, reduces a lot of the incoming damage.
save something like ironbound fortitude, fortifying brew and such for falling ash.