magarena/release/Magarena/scripts/Splinter_Twin.groovy

def Copy = new MagicPermanentActivation(
        new MagicActivationHints(MagicTiming.Token),
        "Copy"
    ) {

    @Override
    public Iterable<MagicEvent> getCostEvent(final MagicPermanent source) {
        return [new MagicTapEvent(source)];
    }

    @Override
    public MagicEvent getPermanentEvent(final MagicPermanent source,final MagicPayedCost payedCost) {
        return new MagicEvent(
            source,
            this,
            "Put a token that's a copy of SN onto the battlefield. "+
            "That token has haste. Exile it at the beginning of the next end step."
        );
    }

    @Override
    public void executeEvent(final MagicGame game, final MagicEvent event) {
        final MagicPlayer player=event.getPlayer();
        final MagicCard card=MagicCard.createTokenCard(
            event.getPermanent(),
            player
        );
        game.doAction(new MagicPlayCardAction(
            card,
            player,
            [MagicPlayMod.HASTE, MagicPlayMod.EXILE_AT_END_OF_TURN]
        ));
    }
}

[
    new MagicStatic(MagicLayer.Ability) {
        @Override
        public void modAbilityFlags(final MagicPermanent source, final MagicPermanent permanent, final Set<MagicAbility> flags) {
            permanent.addAbility(Copy);
        }
        @Override
        public boolean accept(final MagicGame game,final MagicPermanent source,final MagicPermanent target) {
            return MagicStatic.acceptLinked(game, source, target);
        }
    }
]