This one was a lot of fun. There are many different variations by controlling the layers. Make it magical or make it dark and moody. Customize the mockup to fit the theme of your covers!
Make it pretty or evil, it's up to you. At last, my 3-book box set mockup. You'll find an optional “horror” backdrop layer with many other customizations. One of my more advanced mockups but I think with basic Photoshop skills you can achieve the look that you want. Read & Download