agree with zorgi. I have my setup as mage1 ranger2 mage3 fighter4
mages are both glass cannons, so have plenty of ap both to buff/debuff and cast or summon.
mage 1 casts the witch strength buff spell on ranger, slow spell on target, or damage spell
ranger (with bully and guerilla) shoots from stealth on first shot, and uses a special arrow as second shot
mage 3 does same thing for fighter, usually casting an aoe effect on the badies
fighter casts rage, launches attack....
not much survives more than a full turn of that in my experience. hasn't since about level 10.