D.S.P.T. Cannon

As an additional cost to cast this spell, tap an
untapped Knightmare Frame creature you
control.
Choose one—
• Target attacking or blocking creature you don't control gets -X/-X until end of turn, where X is
tapped creature's toughness.
• Destroy each attacking or blocking creature you
don't control with toughness less than half of
X, rounded down.