I went in there fresh with my shammies at eighty five, and the resto totally ran out of mana before the boss died. It took a little more gear to get the group up in sta enough that healing wasn't near as required. I was also spamming heals like Woltk until I realized that nobody needed to be completely topped off and to give the heal totems time to work their magic between his tornado collapses. I remember I even called in a real shaman healer to try and help me get it down and he ran out of mana as well in fresh quest blues and greens.

Side note, that dungeon got a little buffed on Tuesday and I haven't been in there since so it might not be as easy as it was for us coming up a month ago.