I did find that battle to be rather jarring from the simple fact that I was blowing through about everything in site, then I think I was something like 2 shot killed right from the word go.
I need a ton of melee resist just to survive that initial fury from the Divine. So here are a couple hints above and beyond what others presented....
Immediately as the battle starts, jump to the side and get your self clear as fast as you can. Your first target should be the Divine. If you take him out, the battle becomes -MUCH- easier. Use the Pause menu ( the 'f' key) and use your skills to target the divine specifically.
Getting into the cheese territory, it is possible to save the game mid-combat. So if you manage to take out a couple or more of them, save the game (preferrably in a new slot). If you make a mistake after that point, reload and try again until you knock a few more out, save, repeat, until you win.
I finished as a level 34, MM 12, Healing 1, Mana Efficiency 5, Way of Mage 5, Destruction 5, Reflect 12, Evade 9 or some such.
Having those pets out helps alot though
