def PT = new MagicStatic(MagicLayer.SetPT, MagicStatic.UntilEOT) {
    @Override
    public void modPowerToughness(final MagicPermanent source,final MagicPermanent permanent,final MagicPowerToughness pt) {
        pt.set(4,4);
    }
};
def AB = new MagicStatic(MagicLayer.Ability, MagicStatic.UntilEOT) {
    @Override
    public void modAbilityFlags(final MagicPermanent source,final MagicPermanent permanent,final Set<MagicAbility> flags) {
        flags.add(MagicAbility.Flying);
        flags.add(MagicAbility.Changeling);
    }
};

[
    new MagicSpellCardEvent() {
        @Override
        public MagicEvent getEvent(final MagicCardOnStack cardOnStack, final MagicPayedCost payedCost) {
            return new MagicEvent(
                cardOnStack,
                MagicTargetChoice.POS_TARGET_CREATURE,
                MagicSacrificeTargetPicker.create(),
                this,
                "Target creature\$ becomes 4/4, gains all creature types, and gains flying until end of turn."
            );
        }
        @Override
        public void executeEvent(final MagicGame game, final MagicEvent event) {
            event.processTargetPermanent(game, {
                MagicPermanent creature ->
                game.doAction(new MagicBecomesCreatureAction(creature,PT,AB));
            } as MagicPermanentAction);
        }
    }
]