Roth, the Storm

Whenever you cast an instant or sorcery, you may exile target land an opponent controls. Then that player may exile any land you control.
When Roth, the Storm leaves the battlefield, return to the battlefield tapped under their owners' control all lands exiled with Roth, the Storm. Then Roth, the Storm X deals damage to each player where X is the number of lands exiled with Roth, the Storm.