AI have been asked to make a cake with 4 of the Advengers' heads on each corner. I was wondering if I outline the heads onto a piece of wax paper in royal icing and let it dry, will it come off easy (stay together) to place on cake? I don't know of any other medium to use to do this. Any advice would be helpful. Thank you in advance. :)

I used fondant when I did my Avenger's heads. I printed out the characters from my computer, traced and cut them out of fondant and attached to the cake. Here's a pic. If you decide to do royal frosting, make extras in case they break when you're trying to get them off the waxed paper.