You must destroy the blue dungeon, I say this quite a lot but technically you must read : "the blue dungeon heart must be destroyed".

0:10 I'm collecting the lvl 10 imps first then the lvl 5 because lvl 5 imps can be constantly speeded. I don't let imps wander around to prevent them from triggering an action point later and prevent the blue keeper for gaining free rooms. On this map, each time you find/claim a room, this room will be available to all players. 0:38 erratic mouse movement 0:48 this digging scheme is to avoid action points. 0:56 closing the corner 1:17 My imp wasn't killed by a lightning bolt so I wasted some time for you to see what's going on at the enemy heart. I don't care but it's better for viewers, and i don't think it really make me loose time. 1:31 triggering an action point for the samurais 1:56 you must engage the blue imp otherwise he will flee preventing the battle to happen 2:06 this battle is important because barbarians are too slow to reach the blue dungeon and getting rid of the blue creatures will improve the thieves' survival. 2:54 all thieves are alive and hitting the dungeon heart