I do feel the need to ask some questions...even though the search on the site helped me a good ways through the quest.
Where is the goddamn chamber...the goods and the place i´m looking for is the place where I can assemble the riftdevice so i can return it to "I"

[Spoiler]
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When you have half of the rod (gained from the Avatar) you must go back to the unseeing-eye base. There you must talk to the man standing beside the pit of the faithless (and say "the eye is blind") which is on the left-hand side of the base. Go down into the pit and fight your way through the undead village into the Unseeing Eye's Den. Within the den you'll find the other half of the rod (I wont tell you where, you can find it yourself). It will automatically assemble itself. Put it into your quick-slot and use it (the same as you would use a wand) on the Unseeing Eye when he appears then beat the s**t out of him with your fighters. Now take the rod back to the Avatar at the underground temple. Voila -go to the church on the surface and tell them what you've accomplished.