Basic Polygon

var config = {
    width: 800,
    height: 600,
    type: Phaser.AUTO,
    parent: 'phaser-example',
    scene: {
        create: create
    }
};

var game = new Phaser.Game(config);

function create ()
{
    var polygon = new Phaser.Geom.Polygon([
        400, 100,
        200, 278,
        340, 430,
        650, 80
    ]);

    var graphics = this.add.graphics({ x: 0, y: 0 });

    graphics.lineStyle(2, 0x00aa00);

    graphics.beginPath();

    graphics.moveTo(polygon.points[0].x, polygon.points[0].y);

    for (var i = 1; i < polygon.points.length; i++)
    {
        graphics.lineTo(polygon.points[i].x, polygon.points[i].y);
    }

    graphics.closePath();
    graphics.strokePath();
}