The Purging of Gaul

If an opponent controls five or more creatures, The Purging of Gaul costs {2} less to cast.
Destroy all creatures you don't control. Return any number of target creature cards from opponents' graveyards with toughness 2 or less from the graveyard to the battlefield under your control.
Gallia est pacata. -Gaius Julius Caesar, meaning Gaul is pacified.