Star Wars: The Force Unleashed II

In the level in following the Gorog you come to a point in which you become surrounded by these Terror Spider Droids in waves of 20+ or so per wave, with about 4-5 waves accordingly. If you kill all the spider droids and immediately change costumes you can not only net more spider droids but you can also farm Xp!! I've done this multiple times now by simply changing costumes and in about 3 mins I net about 7000+ xp per costume change. If you have both Chaos crystals and destroy the environment around you before entering the room with the spider droids you can get about 650 xp every go. About 7000 xp for 3-4 mins of your time? Not baaad.... Edit: Also- I found that it was very easy while doing the farming to do the achievements for Unleashed (Activate Force Fury 10 times), Lucky Streak (defeat 300 enemies without dying), Passive Agressive (Parry and Counter 10 attacks-real simple: get crowded by spiders and keep pulling the left trigger till it slows down time and follow up with X. 10 times, you're done) and Specialist (since you're farming xp you can choose which force power you'd like to upgrade to rank 3 first. I chose Impulse since you're needing it to farm but once you do this for an hour or so you can easily put another force power to rank 3)

Pretty straightfoward. You will no doubt get this through the stage with the Terror Spider Droids. You know which ones they are, they are the tiny ones. To kill quickly, use Repulse (Hold LT + B) since it tells you when you get surronded by them the first time.

You will almost for sure get this achievement from your first play-through, so you shouldn't worry too much. Repulse is very good for killing these enemies, but I like using saber attacks as well.