Get a group of friends/boosters together and start a Deathmatch. Play as a Mage (Human or Undead) and keep killing your friends until you score 1500 points. You should be able to do this in one game. Must be ranked. You will need 8 people to start a deathmatch.
I think you get about 200 points for each kill depending on how much life the player has when you kill them. The more damage you inflict on them the more points you receive.
If you find this solution to be unhelpful, please tell me why in a comment and I will update it the next time I'm online.