Orthanc
The Treason of Saruman#53 (x1)
Location
2 (1)
Immune to player card effects.

While Orthanc is in the staging area, it gains: "Forced: After the players quest successfully, the first player looks at the top 3 cards of the encounter deck, reveals 1, and discards the others."

Still dark and tall, unbroken by the storm, the tower of Orthanc stood. -The Two Towers