Chromeshell Crab | Magic: The Gathering
Formats Chromeshell Crab is Legal in
Official Oracle Text for Chromeshell Crab
When Chromeshell Crab is turned face up, you may exchange control of target creature you control and target creature an opponent controls.
Official Rulings for Chromeshell Crab
10/4/2004 : The exchange fails if either target is not still on the battlefield at that time.
10/4/2004 : The exchange fails if either you no longer control your creature or the other creature is now controlled by you.
10/4/2004 : The creatures can't attack until you start a turn with them under your control. So you can't swap and then attack.
10/4/2004 : The trigger occurs when you use the Morph ability to turn the card face up, or when an effect turns it face up. It will not trigger on being revealed or on leaving the battlefield.