The Serpent's Redoubt
The Black Serpent#96 (x2/x1)
Location
4 (4)
Desert.   Ruins.  
While The Serpent's Redoubt is in the staging area, it gains: "Forced: After a player plays an ally from his hand, either remove 1 progress from the main quest, or exhaust that ally."

Travel: The first player searches the encounter deck and discard pile for an enemy and puts it into play engaged with him. Shuffle the encounter deck.