Enx-Avian, Mastermind

When Enx-Avian, Mastermind of Doom, enters the battlefield, exert all enemy land, you gain {x}.
{t}, pay 2 life, destroy target permanent.
{t},{w}{g}, Exile target creature or counter target spell.
{t},{w}{w}{w}{w}{w}{w}{b}{b}{b}{b}{g}{g}{g}{g}{g}{g}, you win the game.