first stick em with a massive jolt of high powered lsd
mess with em during the trip... nothing physical.. yet
Then when they come out of it, and come to the point where they regain a sense of self, they might get one of those introspective ordeals , struggeling with with deep concepts like life and death, keep messing... And when they finally snap out of it , and have that deep sense of appreaciation for "life'... start the real carnage...go medieval on their ass
Gotta make it count, can't torture a scumbag to death twice, unless you get the ego broken with something like acid that is