You all are thinking too small.
On top of this card making you win every game it can also allow you to do more than just win. Such as, "This card allows the user to alter Elements the Game however they choose". This would be the ultimate power within the limits of the game. So now what are the limits of the game?
If the card's mechanic was not confined to the game it could make you the king of the earth, let you change reality as you please etc. Though this is not possible like the title states it needs to be. Although total power is not possible through this, the game could conceivably be changed in a way that makes the changer of the game a lot of money and power.