We finished the Drootorca Cavern and are doing the Kor Well puzzles now... and I'm looking at the last chapter and trying to figure out how to cut and paste the last bits all together. I don't think it makes sense for there to be a dungeon after the final BBEG fight so I think I'm going to strip the tomb sequence down to maybe three rooms:
The outer tomb has carvings depicting Taargick as leader and proud defender of dwarven legacy, and Stoneriver awaits in this chamber like the grail knight in Indiana Jones and the Last Crusade... This encounter can play out as a social encounter: he poses a sphinx-like riddle that is designed to test if the players have internalized the broad messages of the campaign
Consider carefully the way you go
Which path will forge dwarven morrow
Two doors, one fore, one behind
The way of progress is yours to find
Stay the course with Toragg's pantheon
Or return for Felgunn and rivethunn
If they advance forwards, Stoneriver announces that it seems Taargick's secrets shall remain sealed until others come bearing Skysunder and a teleportation circle activates, retuning the party to Highhelm... roll credits with a montage of the heroes defeating the forces of the Ash Engineer (who was another antagonist throughout my playthrough)
If they go back towards the door they entered by, Stoneriver nods solemnly and tells the party that his time watching the tomb has come to an end, and he returns to Toragg's side with a dimension door.
The second room is a corridor with friezes depicting the hard moral choices that Taargick made during the Quest for Sky summarizing the content of the four visions and the original Stoneriver questions
the voices of opposition to return or to stop halfway
the sacrifices of the people, young and old
the choice of mercy for even fearsome foes
The third chamber is vast and empty and engraved with the directions back to Felgunn in a pattern that can only be completed by inserting Skysunder into a backlit slot so the light shines through the gem in the pommel. ... roll credits with a montage of journeys through the Darklands ending at an opening of a cave giving us a teasing peak of Felgunn