action('Attack') {
    allowFor {
        ownedBy 'active'
        zone 'Battlefield'
    }
    requires {
        require card.sickness == 0
    }
    targets 1 of {
        ownedBy opponent
    }

turnEnd {  // perform on end of turn:
    if (you == null) {  // if you are defeated...
        return          // ...return from this method
    }
}

    action('Use') {
        allowFor {
            ownedBy 'active'
            zone 'Hand'
        }
        cardTargetFilter()
        effectAction()

        cost MANA value { card.mana_cost } on { card.owner }

        perform {
            it.destroy()
        }
    }

List<Invoice> invoiceList = new ArrayList<>();
//populate
BigDecimal result = invoiceList.stream()
        .map(Invoice::total)
        .reduce(BigDecimal.ZERO, BigDecimal::add);

// instead of:
    action('Play') {
        allowFor {           // only allow if...
            ownedBy 'active' // ...card is owned by active player
            zone 'Hand'      // ...card is on hand
        }

// do this:
    action('Play') {
        /**
         * only allow if...
         * - card is owned by active player
         * - card is on hand
         */
        allowFor {
            ownedBy 'active'
            zone 'Hand'
        }

action('Play') {
    /** Only allow if... */
    allowFor {
        /** ...card is owned by active player */
        ownedBy 'active'
        /** ...card is on hand */
        zone 'Hand'
    }

        //if river
        IsoDirection sideToStart = IsoDirection.values()[this.game.random.nextInt(IsoDirection.values().length)];
        IsoDirection oppositeDirection = IsoDirection.opposite(sideToStart);
        IsoPoint startPoint = this.edgePointForDirection(sideToStart);

        for (int i = 0; i < CityWorld.WORLD_HEIGHT; i++) {
            startPoint.move(oppositeDirection, CityWorld.WORLD_WIDTH - 1);
            Tile firstTile = world[startPoint.x][startPoint.y];
            firstTile.setBuildingType(IsoTileType.WATER01);

public void randomMoveTowards(IsoDirection direction, int bounds) {
    Random random = new Random();
    int randomNumber = random.nextInt(2);
    switch (direction) {
    case LEFT:
    case RIGHT:
        if (randomNumber == 0) {
            this.move(IsoDirection.UP, bounds);
        } else {
            this.move(IsoDirection.DOWN, bounds);
        }
        break;
    case UP:
    case DOWN:
        randomNumber = random.nextInt(2);
        if (randomNumber == 0) {
            this.move(IsoDirection.LEFT, bounds);