I'm at school, so i'm not thinking at my best, but here goes:
The quest starts in ethren. There is a guy in the shadowy deadend hallway. He tells you about an ancient tower with magical weapons that can destroy the evilest of evil. The tower is in a high place, like where Centuria is. The tower is divided into different sections. The first floor has low level mosters, like goblins and stuff. One of the goblins drops a key you need that opens a door to another section of the tower. That section has orcs, you get a key, goes to ogres, next goes to undead, etc. At the top of the tower, after demons, you fight the god of battle, a high level thing, even higher than the guys at CH. He drops an amulet that you take the guy in the mage tower, and he summons a weapon from an another dimension, depending on what class you are, like fighters get a Chaos Blade and and mages get an Aura Shield. You can also turn in the amulet to the guy in ethren for exp and money.
Cool, eh?