Demoralizing Slaughter

If you or a creature you control destroyed an
opponent's creature this turn, all of that
opponent's creatures that they control with
power or toughness lower than 4 have -2/-0
until the end of that opponent's next turn.
The draconic aura was bad enough. When they
witnessed their comrades eaten alive or reduced to
acidic slag, the infantrymen broke ranks and fled.