magarena/release/Magarena/scripts/Turn_the_Tide.groovy

[
    new MagicSpellCardEvent() {
        @Override
        public MagicEvent getEvent(final MagicCardOnStack cardOnStack,final MagicPayedCost payedCost) {
            return new MagicEvent(
                cardOnStack,
                this,
                "Creatures your opponent controls get -2/-0 until end of turn."
            );
        }
        @Override
        public void executeEvent(final MagicGame game, final MagicEvent event) {
            final MagicPlayer opponent=event.getPlayer().getOpponent();
            final Collection<MagicPermanent> targets=
                game.filterPermanents(opponent,MagicTargetFilter.TARGET_CREATURE_YOU_CONTROL);
            for (final MagicPermanent target : targets) {
                game.doAction(new MagicChangeTurnPTAction(target,-2,0));
            }
        }
    }
]