The Wilds of Rhovanion #50 (x2/x1)
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While Hobgoblin is guarding a card, it gets +X +X and +X where X is that card's cost.

Forced: After Hobgoblin enters play, the first player attaches the top card of his deck to Hobgoblin faceup as a guarded attachment. When Hobgoblin leaves play, return the card it was guarding to its owner's hand.