DC Comics just released the Cover to Batman and Robin #13 over at The Source. The cover done by Frank Quitely features the Joker who was the big surprise reveal in Issue #12.
Official Description of the Issue - In "Batman Must Die!" part 2 of 3, one of our heroes lies near death! Dick Grayson and Damian Wayne enter the ultimate, blood-soaked battle against two foes who almost destroyed the original Batman. Are the new Dynamic Duo up to this final confrontation with absolute evil? If they can't truly bond as a team, they're dead!