Lying in Wait
The Blood of Gondor#129 (x4)
Treachery

When Revealed: The first player turns each hidden card in his play area faceup. Resolve the "When Revealed" effects of each encounter cards turned faceup by this effect. If a location is turned faceup, add it to the staging area.

Up came the Orcs, yelling, with their long arms stretched out to seize him. –The Two Towers