The image is of Ironman standing so I will make a 9X13 cake. I want to do more than just putting a border around it. Any ideas to change it up? Make it unique and different? Thanks.

Any kind of fondant cutouts that relate to the theme? You can scatter them around the cake instead of just a border.

Good idea. The background is dark but I could maybe do some flames around the side. Thanks!

Take your flame images, put them on fondant and cut them out, this will give a 3d ish look!