The Snazaroo special effects face paint kit would be perfect for painting gruesome Halloween faces as it comes with sculpting wax and fake blood. (In fact, two types of fake blood -- one in a cake form, like the other face paint colors, and the other a gel.) Of course, you don't have to use it for face painting designs involving blood; with green, black, and white paint you've the ideal colors for an ill-looking witch or monster!
