Ring World

Exile all Land permanents you control.
You may not control any other Lands while
this card is on the field.
{t}: Add two mana of any combination of colors
to your mana pool for every Land exiled by this
card's effect.
{t}, Sacrifice Ring World: Destroy all Creatures
and Planeswalkers on the battlefield.
When this card is destroyed, return all Lands
exiled by this card's effect to the field.