Well, Ozzimandias, you've certainly stirred things up!
Just because there's no entrance to the dungeon doesn't mean the map is unplayable.
P.S.: We contacted the map's author and found out that the author removed the dungeon entrance due to balance issues, so it's not a bug. The scenario is working. Also, it turns out that the author has a newer version of the scenario with an entrance to the dungeon! So, an update will be available soon!
Dear atlant108, when you can't access the dungeon where the last castle is located, that's not balancing; it's a genuine bug, and there's no excuse for it.
Or do you know some special way to get into the dungeon and actually finish the map?
If so, I'd be glad if you could share it.
Judging by the comments, I'm not alone in my frustration with the map's unplayability.