: 3rd siege of Myrgard by the Ghol :) during the SB war.
Is there any evidence the ghols tried to retake Myrgard? Hmm. Mb better to wait till you've played the Myrgard-based levels in M3, and if there's any loose ends in the story there you could take them up.
: BTW why dont the Dwarves go back to stoneheim? Or did
: they?
They hadn't yet. Perhaps because they were too busy resettling Myrgard, and also because it would be a formidable undertaking. As the barbican at Stoneheim was collapsed, thereby entombing the citizens, this implies that the vast bulk of the city was underground & is inaccessible to ghols and dwarves alike, so perhaps there isn't much left to retake.
As a general idea, it might be better to concentrate on storylines based on M3 rather than M2 or TFL, as many new M3 players wouldn't be familiar with the other episodes, and hence may not relate to your plugin that well.
cheers
Iron