Forum:The right way to use Mist Vally Falcon?

My buddy and I were just having a casual duel until the question of Mist Valley Falcon's effect came up. As stated: "This card cannot declare an attack unless you return 1 card you control to its owner's hand."

But the main question that my friend pointed out is "where in the statement does this card state you may return a card to your hand." and the card specifically says "unless you return one card."

Basically meaning do I need to use another card's effect, such as the likes of Mist Valley Thunder Lord which specifically states "you can select and return 1 card you control to the hand" in order to attack with Mist Valley Falcon?

Thanks for all feedback and input! :)