A Cunt with Power is someone who has been promoted in an organisation (often via unscrupulous means) and proceeds to abuse their authority. Everbody hates them and when they die a day of celebration will be held.
Mark is a Cunt with Power and he threatens to fire people if he can't win an arguement with them.
When someone, usually a girl, is so despicable as a human being, that they cannot just be considered as "bitch" or a "cunt;" they must be a bitch to the exponent of "cunt" to describe how incredibly awful said person is.
Boss: I cut your wages again, and I will also expect you to come in on Saturdays. You had done nothing wrong, I just needed to feel better about myself.