Reign of Terror

At the beginning of each players upkeep, that player chooses an opponent at random. Then both players
reveal the top three cards of their library. Both
players put a creature from among those cards onto
the battlefield without paying its mana cost. The two creatures put on the battlefield this way fight each
other. If a creature were to die this way, its controller
loses life equal to that creature's total mana cost.
"Alright then, let it be fear."
—Daenerys Targaryen