Here's a middle game puzzle.
Instructions: In this position Black played 1. .. Rxd4.
a) With that move Black gave away the win.
b) The resulting endgame is draw, however Black couldn't achieve more than that anyways.
c) Black gets clear advantage now.
Together with your answer you also have to give detailed explaination why you chose this or that answer. This requires detailed analysis of all the possible variations.
Hope this isn't too difficult for you. If you like it, I have a book with 120 middle game puzzles and another with 120 endgame puzzles like this one.