magarena/release/Magarena/scripts/Wrack_with_Madness.groovy

[
    new MagicSpellCardEvent() {
        @Override
        public MagicEvent getEvent(final MagicCardOnStack cardOnStack, final MagicPayedCost payedCost) {
            return new MagicEvent(
                cardOnStack,
                MagicTargetChoice.NEG_TARGET_CREATURE,
                this,
                "Target creature\$ deals damage to itself equal to its power."
            );
        }
        @Override
        public void executeEvent(final MagicGame game, final MagicEvent event) {
            event.processTargetPermanent(game,new MagicPermanentAction() {
                public void doAction(final MagicPermanent creature) {
                    final MagicDamage damage = new MagicDamage(
                        creature,
                        creature,
                        creature.getPower()
                    );
                    game.doAction(new MagicDealDamageAction(damage));
                }
            });
        }
    }
]