Thor

When the only other players are Earth, their teammates, and your teammates, reveal Thor.
You all win. When there is no Earth, you lose.
You may flip this card face up at any time. When
you do, create an artifact called Mjolnir that has;
{t} Mjolnir does 1 damage to any creature or planeswalker.
{3}{t} Destroy target permanent an opponent
controls. Mjolnir can't be untapped this turn.
{1} Untap Mjolnir.