This was my party build on hard mode, it's the best party build that I've discovered so far and I very rarely ever died on any character.
Front Row:
Minotaur - Fighter - 50 Unarmed Combat
(Uses full heavy armor, makes a decent tank. Unarmed combat does massive damage)
Lizardman - Rogue - 50 Dodge
(Uses full Lurker set & scaled cloak, he’s an evasion god, dodges about 95% of the time on the harder monsters. I soloed the Fighter's Challenge with him

)
Back Row:
Lizardman - Rogue - 50 Assassination, rest in Dagger
(Uses Assassin’s Dagger and any gear that gives strength. I used the EXP pendant and all skill books on him. If he gets a backstab off it almost always single shots any monster, even Ogres and Goromorgs)
Insectoid - Mage - 50 Ice Magic, rest in Spell Craft
(Uses Frostbolt often, so my assassin can backstab the monster which usually single shots them)