magarena/release/Magarena/scripts/Abyssal_Nightstalker.groovy

[
    new MagicWhenAttacksUnblockedTrigger() {
        @Override
        public MagicEvent executeTrigger(final MagicGame game,final MagicPermanent permanent,final MagicPermanent creature) {
            return (creature == permanent) ?
                new MagicEvent(
                    permanent,
                    permanent.getOpponent(),
                    this,
                    "PN discards a card."
                ):
                MagicEvent.NONE;
        }
        @Override
        public void executeEvent(final MagicGame game, final MagicEvent event) {
            game.addEvent(new MagicDiscardEvent(
                event.getPermanent(),
                event.getPlayer()
            ));
        }
    }
]