magarena/release/Magarena/scripts/Niblis_of_the_Urn.groovy

[
    new MagicWhenAttacksTrigger() {
        @Override
        public MagicEvent executeTrigger(final MagicGame game,final MagicPermanent permanent,final MagicPermanent creature) {
            return (permanent == creature) ?
                new MagicEvent(
                    permanent,
                    new MagicMayChoice(MagicTargetChoice.NEG_TARGET_CREATURE),
                    MagicTapTargetPicker.Tap,
                    this,
                    "PN may\$ tap target creature\$."
                ):
                MagicEvent.NONE;
        }
        @Override
        public void executeEvent(final MagicGame game, final MagicEvent event) {
            if (event.isYes()) {
                event.processTargetPermanent(game,new MagicPermanentAction() {
                    public void doAction(final MagicPermanent creature) {
                        game.doAction(new MagicTapAction(creature,true));
                    }
                });
            }
        }
    }
]