Core work requires time, patience and perseverance. Master Plank is a workout that works the core and abs providing stability and enhanced athletic performance. The Plank, of course, recruits a lot of other muscle groups in a small way which is an additional benefit. It is your core, however, that it will work and it is there that you will feel the benefits of this workout, particularly if you also add EC.
Extra Credit: Keep the plank throughout, don't drop down.