Ancient Barrow
Fog on the Barrow-downs#8 (x3/x2)
Location
X (4)
Ruins.   Downs.  

X is 1 plus the number of facedown cards under this location.

Forced: After Ancient Barrow enters play, each player places an ally he controls facedown under this location. When Ancient Barrow leaves play as an explored location, return each ally under this location to its owner's hand.