For this you need the lift and slam ability. I play on controller, so I'm used to those controls. Anyway, under Force > Telekinesis, unlock the following skills:
Wrenching Pull (1 point)
Soaring Lift (2 points)
Mass Slam (2 points)
Gravitational Mastery (1 point)
The last one isn't needed for this achievement but if you have it, you don't need to use Wrenching Pull (
+
) like you might need to without it.
Now, go to the Automated Forge on the Shattered Moon. Go down the corridor (you'll get attacked but the aggro helps kinda), right at the door, through the next corridore into the room, killing the guy hiding on the left in the middle of the room.
Regular Slam (
+
) only slams one enemy. To slam multiple enemies, press and hold
+
(hold both buttons). You can also use Slow to help.
+