Berkeleian Chess is one of the most bizarre theme in a puzzle.This is how it works,any piece,including the king,that is neither attacked by an ememy piece or not protected by a friendly piece is removed from the board.

Every piece right now,on both sides is either attacked or protected,or both,you now need to make a move,either a white OR black one,that will set in motion a chain of disappearing pieces resulting in a completly clear board.You can only make ONE move,which move?