Be careful if you use a word that is both a noun and a verb; you could run into the same problem faced by the writers for the Yahoo! front page.
As a verb foil means thwart. As a noun, it refers to someone who “by contrast underscores or enhances the distinctive characteristics of another.” Oliver Hardy was a foil for Stan Laurel; Dean Martin was a foil for Jerry Lewis. And Virgil Goode can both thwart Mitt Romney’s bid for the presidency and underscore the Republican’s characteristics. If that’s possible: