I picked up a note some time in the game, think it was after I killed a dragon, that was part of a Thunder hammer artifact. I spoke to that dwarf Cromwell who fixes the artifacts and he said I needed some more stuff .. I can only remember that I also needed the "Gauntlets of ogre strength/power" which I don't know where u get ): It also needed two more pieces but I have no clue where they're found in the game either
Cromwell said it would be worth my time to get it so I figured I'd see if anyone had completed the quest and can enlighten me on how to get it!
Cheers (:

You need 4 items for the Crae Fang the suped up hammer of thunderbolts.
1) The scroll off of the Shadow Dragon.
2) The Hammer of Thunderbolts (mindflayers in side room from sewer)
3) Gauntlets of Ogre Power (Planar Sphere off a canibalistic halfling)
4) Girdle of Frost Giant Strength, Kuo-Toan area of underdark. Need to do an animal summoning 1, kill it on the statue, and then fight the nasties.

aha!

Thanks man (:

But how do you get into the secret mindflayer room? You need a key, but I can't find it =(

The key is located in the Windspear Hills dungeon. For the *exact* location, you can reference our walkthrough at http://www.gamebanshee.com/baldursagateii/

Hope this helps.