Bard (Two if you want mana factory and to go really overboard),

Invoker - seven path

Healer

Tank (def shifter, certain warrior builds, to be honest with all the dr from healer, invoker, bard just about anything decent can work)

More Damage output (Good AP, Warrior, Ranger (in some areas), conjurer, offense shifter, ect)

Double bard plus healer can evenually kill just about anything since you have the mana song to keep the healer healing, tones of DR, more healing from the bards if things get rough.

(Note my setup is pretty much just a generalization of what you said)