Dungeons can score of each other. As they are considered a different tile if they are no dungeons on the other sides. Jeff could have placed his third dungeon below his first thus clearing that lower corner for a swamp would have been an extra 6 points.
This looks great. Jeff, just to be honest with you, Jamie could have even scored more if I am not mistaken by putting the graveyard monster from the cloud tile to the graveyard tile in the top right corner ;) Unfortunately, my boyfriend with whom I mainly play is not so much into tile placing/puzzle games.