Great Plateau

Great Platue enters the battlefield tapped
unless its controller sacrifices another land.
{t}: Add one mana to your mana pool that a land
you control could produce.
{3}{r}{g}: Great Plateau becomes a 5/5 red green elemental creature with "Exile a tapped land you control, place a creature from your hand onto the battlefield" until the end of the turn. It is still
a land.