God King, Destroyer of Worlds

When God King, Destroyer of Worlds is used to
block damage, attack all opponents for X, where
X is the total amount of damage opponent
attacked his owner for that round.
{x}: Put God King, Destroyer of Worlds in the graveyard, or command zone if he is a
commander, and any non-land permanent card
with mana value X or below is sent to graveyard.
I am the consensus.
—God King, Destroyer of Worlds