Second round of play testing started with the players exploring the main hall of the dwarven mines and the treasury. The rogue quickly determined that the lock is a well made and tricky one, requiring one or several minutes of peace and calm to pick.
Simultaneously the elven barbarian kept lookout, and that was a good thing, because she saw first one, then the other, of the two doors open, and goblins pour out into the hall! The adventurers felt trapped, and I allowed them ample time to discuss what to do...