Playing Balin's expedition and his son and heir was able to slay the Balrog and survive, so I've been slowly taking back the Misty Mountains. Its one thing to need to fabricate claims on orcs as a Dwarven ruler, but vassalizing them afterwards pretty much necessitates you revoke their title and defeat them in a civil war, taking extra time and money. It would make more sense to just execute all orcs in the court and force change the religion/culture while giving you the holding to distribute.

I know this is the case for most invasions, but there are still plenty of cases I ran into after claiming all of Gundabad and conquering it, and in Goblin Town.