Ico and Yorda, Castlebound

When Ico and Yorda, Castlebound enters the battlefield, target opponent creates a colorless legendary artifact land token named Castle in the
Mist with shroud, indestructible, and "{t}: Add
one mana of any color."
Whenever Ico and Yorda deals combat damage to
a player, that player sacrifices an artifact. If
Castle in the Mist is sacrificed this way, exile Ico
and Yorda at the beginning of your next upkeep.
When you do, you win the game.