you go to the pit in whitegate and talk to the fat guy left of the entrace to the 1st cage, you trade him any imperial currency for jettons. bronze is 1, silver is 10, mythril is 30, and gold is 200. soultrapper costs 2 jettons, soultrapper 2000 costs 500 jettons, and i think there is a 3rd version of the soultrapper for 1000 jettons but ive not tried for it cus i think it might be a waste of imp standing.