The Overmage of the Cinbri - Act 3 Broken World Story Quest
The Overmage of the Cinbri is the final Story Quest in the Broken World Expansion Pack for Dungeon Siege 2. It begins immediately after you complete The Dwarves of Glorydeep and all you need to do for this quest is to find the Overmage and defeat him. This entire area is rather linear so you won't have any trouble finding him unless you get turned around.
Along the way you'll be able to collect the Cinbri Gem which is the final item you'll need for The Ancient Tome Side Quest. You'll find this item in one of the big rooms throughout the area sitting on a shelf, it's pretty hard to miss. Other than this item there will be no other quests to complete along the way.
When the linear path ends you'll find yourself in a large circular room with the Overmage in the center. I strongly recommend you stock up on Potions if you are low on them then speak with the Overmage to begin the final boss fight of Broken World.
How phase 1 of this boss fight works is the Overmage will start off invulnerable and he'll summon a wave of enemies for you to fight. Defeat the wave of enemies and then the Overmage will become vulnerable to your attacks for a couple of seconds. Deal as much damage to him as you possible can during this time. Powers like Brutal Attack or Take Aim are the best to use on the boss when he is vulnerable. The more damage you deal to him the less waves of enemies you'll have to fight over all.
As always you'll want to use 'Mirror Mode' for almost the entire fight. You don't want your party members attacking the boss while he is invulnerable instead of the enemies and you don't want them standing around during the key moments the boss is vulnerable.
If you don't frequently use the Spacebar to pause your game I strongly recommend you do during this fight. Some of your Powers (like Provoke) will be useful when adds are summoned but others (like Brutal Attack) are useful when the boss becomes vulnerable. Pause and switch between these Powers throughout the fight.
Once you beat the Overmage during Phase 1 he'll transform into Zaramoth Reborn and you'll start phase 2 of the fight. During this phase you'll want to approach him like a normal boss; he doesn't have any one shot mechanics (unless you have really low Resistances) and no real unique strategy. Whack him and keep chugging Potions until he goes down.
Speak with Kirani in the room once the fight is over to complete this quest and allow you to move on to the next difficulty of Dungeon Siege 2.