This achievement can only be attained if you are play either on Bane’s or Joker’s Gang, nevertheless it will be much easier if you are on Bane's team, especially Bane himself.
The best way to get easy XP is to than capture control points (150XP) and use your Tactical Darts to shock either the players on Joker's Gang or the Heroes (250XP). Also, you will also earn 1000XP if you win the match and 500XP if you lose. You can always check your XP during the match by pressing back botton, on your controller. The achievement will unlock at the end of the match.