Prospective Covering Letter Gimmicks In Job Applications?

Gimmicks in job applications? - prospective covering letter

I worked for the NHS and decided to change your career and jump into the market to have. I realized that the brand, public relations, advertising agencies and creative people are very specific in selecting the right candidate. I'm more into account management and strategic planning, although I have no experience with it so far, I have a degree in marketing, but never used in my professional life.
When I realized my resume with a very original letter (future), and called me for an interview, or this will be my death sentence?