magarena/release/Magarena/scripts/Change_of_Heart.groovy

[
    new MagicSpellCardEvent() {
        @Override
        public MagicEvent getEvent(final MagicCardOnStack cardOnStack,final MagicPayedCost payedCost) {
            return new MagicEvent(
                cardOnStack,
                MagicTargetChoice.NEG_TARGET_CREATURE,
                new MagicNoCombatTargetPicker(true,false,false),
                this,
                "Target creature\$ can't attack this turn. " +
                "If the buyback cost was payed, return SN to its owner's hand as it resolves."
            );
        }

        @Override
        public void executeEvent(final MagicGame game, final MagicEvent event) {
            event.processTargetPermanent(game,new MagicPermanentAction() {
                public void doAction(final MagicPermanent creature) {
                    game.doAction(MagicChangeStateAction.Set(creature,MagicPermanentState.CannotAttack));
                    if (event.isBuyback()) {
                        game.doAction(new MagicChangeCardDestinationAction(event.getCardOnStack(), MagicLocationType.OwnersHand));
                    }
                }
            });
        }
    }
]