The War on Three Fronts

(As this Saga enters and after your draw step,
add a lore counter. Sacrifice at III.)
I: Destroy target artifact or land.
II: Exile all cards from an
opponent's graveyard.
III: The War on Three Fronts deals X damage
divided as you choose among any targets. X is
equal to the number of cards your opponent
controls in exile. Tap each creature
dealt damage this way.