Search for the Chamber
The Fate of Balin
The Mines of Moria#8 (x1)
3A-B (20)
When Revealed: The opposing team searches the top 5 cards of the encounter deck for a card with cost 2 or less (cost 3 or less instead if there are two or more players), sets it aside, and shuffles the encounter deck. Reveal the set aside card. Its 'when revealed' effects cannot be canceled.

Your journey through Moria has been marked by all manner of terrible hazards, but you've discovered no sign of Balin's company. You hope that you might find some record of the Dwarven colony in the Chamber of Mazarbul.
Forced: At the beginning of the staging step, the first player must choose: either reveal an additional encounter card this phase, or no more than 5 progress can be placed here this phase.

This stage cannot be defeated while Chamber of Mazarbul is in play. When this stage is defeated, the players win the game.