Ok, one from me for all the help I got here: ICEMAN
This was one of the hardest for me:
Get Polar Explosion + frigid aura for him. Frigid aura makes Iceman immune to the jump of the little creatures. Just head for Mephisto's pets and let others do suicide on frigid aura.
If you see the zombie type enemy, just throw them from a ledge, they take too much time to kill.
When you see the first fire giant, hit "x" and do the quicktime event to get his sword. Kill some enemies.
Ok, now the important part: When you come to the area of the 2nd giant, just take your time to kill the enemies from afar, don't aggro the giant. When they are killed, get the sword, kill the giant and get in. Now you have a sword that is still good to kill 25% of the hp of the enemy.
Tactics on boss:
The boss can really only do some dmg with melee, his casting abilities are weak. So run around and when you are far away from him (his teleport thingy is a good time to get some space between you and him), start casting. Now wait till he is very close and shoot him with a fully charged polar explosion. You have to wait or you are going to miss him. When he stops to cast, try to get a shot in. But always use fully charged PE's or you run low on energy and you don't want to melee him.
If you have still questions, feel free to ask.
I have done gold on all missions on normal and between levels 35 and 45 btw.