There are 2 force powers that can not be farmed in the prologue:
With Force Lightning I unlocked it by the end of my Sith Master Difficulty run. If you are short any by the end of the game, just replay the first level and spam that ability.
Lightning Shield is a bit trickier, to be honest. If you have the Jedi Temple DLC, then this will take you ~45 minutes (at most). If you don't then it will take you a bit longer
The Jedi Temple has an area with an unlimited enemy spawn - the droid training room. Playing this on easy, and getting to the room will take a few minutes (max). When you reach the room, and the animation ends (droids spawning, doors shutting, etc) start taking out the lightsaber droid spawns. These guys are annoying and will mess up your rhythm rather than give you kills. You want the droid force users (their spawns are on the second level
Also, please make certain that you have this force power fully upgraded for maximum effectiveness.
Once the droid force users are the only enemies spawning, stand underneath one of the spawn points. Enemies will jump down from the second floor (maximum of 4 at a time). Charge you lightning shield, and when all four are in the room release it. Lightning will arc out of the shield killing all four before the ability ends. Then you just rinse and repeat.
I had about ~10 to 20 seconds for every 4 enemies, so worst case I was looking at 12 enemies a minutes.
12 (enemies) x 45 (mins) = 540WITHOUT DLC:
I found that the first area (TIE Fighter bay) on the first mission was a great place to knock out this trophy (if one doesn't have the DLC
). There is a lift in the room that will bring a group of storm troopers into the center of the room...3 times. Each group has ~8 to 10 enemies, however you need to take out Kota's men or they will just gun them down before you can farm the troopers
This method seems like it may save time (24 to 30 kills minimum with Lightning Shield?!?
) however if you want to effectively farm this location you need to continually save, then restart at checkpoint when the enemies are defeated. Loading screens, getting back to the room, etc really add time to this method.
Of course, you could just run through the level taking everyone out with Lightning Shield as well, and you would probably have this trophy done in 5 or 6 runs (still taking awhile with a run being around 20 minutes