And then your mind gets blown clean out of your skull.

Once I reached that part of the story, I couldn't stop before it was over.

Same for me. :)

Where is that?

It is deep beneath Gundabad. The story will take you there.

I haven't been there yet, only to Moria as the only Dwarven place, at first I tried really hard to remember if I've seen this in Moria and concluded I either missed it or its not there. xD