I made this scary Exorcist Costume by taking an old night gown and mixing up a nice green pea soup color and painting it on the front of the gown to make it look like she threw up on herself, like in the movie The Exorcist. I also got some old house shoes for her to wear.
She has some pretty wild hair anyway so it worked out perfect for her to be Ragan. I blacked out her eyes to make her look scary and added some zombie tattoos that I cut up to make it look like she had scratched herself on the face. I put some green face paint around her mouth and down her neck as well. We took gauze and wrapped it around her wrist to make it look like she was tied to the bed at one point.
This costume was a quick, cheap and easy build.