jimmytheccomic
First Post
I can't see how the module would be negatively impacted by milestone leveling to 5th level once the party gains the Stone of Golorr and determines what the keys are. As that's the mcguffin for the entire story, gaining possession of it seems reasonable place to gain a level. And the only real change would be to make the discovery of the gold come at 5th level instead of 4th, which, again, doesn't seem like too major of a change.
The real question is how this segues into Dungeon of the Mad Mage. If the first level there is tuned for 5th level adventures, your group might be stuck at level 5 for awhile. Then again, that's not too bad of a level to spend some time in...
The segue isn't incredibly strong, I have a hunch that a lot of DMs are going to put the vault in a deep level of the Undermountain.