Can someone explain to me how this "magnificent bastard" thing started? What does it refer to?
Patton.
Patton used in in reference to Rommell in WWII.
Patton read one of Rommel's books on Armor tactics... then whomped on Rommel and made the "You magnificent bastard! I read your book!" Remark (at least according to the George C. Scott movie version).
The line is a take off from a bit of dialog George C. Scott said in the Movie Patton.
When Patton went up against Rommel he kicked his butt and the line in the movie is (as Patton is watching through his binoculars the American tank forces administering the Butt-kicking to Rommel's troops) "Rommel you magnificent Bastard, I red Your Book!"
Rommel had written and published a book on tank warfare and Patton had immersed himself in it prior to battling Rommel. So Patton knew exactly what Rommel would do in such a battle and deployed his forces to take advantage of such.
Thusly the line is used for Rove (The Most Magnificent of ALL the Bastards) because he knows the Democrat's play-book and deploys his forces to exploit their weaknesses.y