Necromancer's Pass
The Wizard's Quest #13 (x2)
2 (2)

When Revealed: The first player chooses a card in his hand. The opposing team looks at the first player's hand and chooses a different card to place faceup under Necromancer's Pass as a guarded objective. While Necromancer's Pass is guarding a card, copies of that card cannot be played. When Necromancer's Pass is explored, return the guarded card to its owner's hand.