I love the Life Splinter combo in which you play a single, strong tank in the frontline (like the Shieldbearer), then 2 healers (Divine Healer + Venari Crystalsmith), and finally the Armorsmith. It's almost impossible to kill the Shieldbearer, as he'll be receiving 2 heals + 1 armor repair every turn.

It's a very strong strategy that, on its own, is able to bring you to the higher ranks!