Depends on your party, but what I do is pull everyone back to the top of the tunnel that leads into that room. Buff everyone with everything you've got. Send a character down to pull them up the narrow corridor to your waiting party. Lay out a field of AoE spells - web, spike growth, grease, and if you have them: skull trap, fireball (once they're trapped in the brew), and maybe Silence 15' Radius (to shut up those bloody priests if they're hanging behind). Hit anything you can see with ranged weapons. Finish off the trolls with the fire pots. By the time your AoE spell durations run out, you should pretty much have wiped the floor with them. If there still seems to be a fair number of them left, then refresh any spells that run out. This always works brilliantly for me.

*edit* The character pulling the mobs should be hasted. (Well, everyone should). That way he can run back to your party fast enough that you still have time to lay out that brew of AoE spells after he arrives back and he won't get caught in it.