I agree with gremlin. I can't remember the details, but my character was very strong with ice and my rogue archer was strong in fire. It worked quite well in many parts of the game where I froze the enemy and the archer finished it off with fire. In the battle with Duriel, I think I kept more than one Town Portal open and of course, loads of health potions. I don't think I used a speed potion, but that's not a bad idea.
The one thing I do remember is that it took me a long time to defeat Duriel!
If life gives you lemons, make lemonade. If life gives you tomatoes, make Bloody Marys.