Battle of Ages

(Start the game with this card in face-down in exile.
You may turn it face-up when a creature deals combat
damage to you. This card then does battle with that
creature. After the battle, remove this from the game.)
_________________________________________
When Battle of Ages does battle, flip a coin. If
you win the flip, Battle of the Ages deals 4
damage to the creature it's battling. If you lose
the flip, it deals 2 damage to that creature
instead.