Champions of the Shoal (Lorwyn Eclipsed 356) - Rare Magic: The Gathering Card

As an additional cost to cast this spell, behold a Merfolk and exile it. (Exile a Merfolk you control or a Merfolk card from your hand.)Whenever this creature enters or becomes tapped, tap up to one target creature and put a stun counter on it.When this creature leaves the battlefield, return the exiled card to its owner's hand.