In Chapter 12: The Aquaduct, when you reach the point where there is a save point near the main door (which leads to a huge statue of the girl, with three water weights around her), save the game. Turn around and face where you came from. Take a few steps and turn to the left path. You will see a small door, like an elevator. Go in there, and press L2 to display your Karma. The first time you go in, kill all the Scorpion-looking things and remember the total number killed. This number will appear on your Karma display. Return outside and save the game if desired. Go back in, but do not kill all of them. Leave when there are two to four of them remaining. Go back in and they will appear again. Repeat this as many times as desired.