I don't think Chuck tortures or murders. or at least not in the primary sense of the words. the game is all about kinks and fetishes, anything sexual. Warren is already the one that likes to inflict wounds during sex. Chuck doing the same does not make sense and is not necessary.
It's more likely that he enjoys breaking women mentally. with a bet that says if he ever wins, they let him do whatever he wants without limit. it's still a porn game, so he most likely breaks them through some kind of extreme sexual pleasure without giving them rest. he probably likes imprinting himself on his "victims" that way, and making them unable to enjoy sex normally ever again.
the "lasting damage" comment to Sophia, I think Chuck means Sophia is so formidable that she would recover from what he'd do to her. it's not about him sparing her. he gives a speech to MC about control. so he probably completely lets go of any control once he wins a bet. and that's probably why Sophia and Kathleen think the drug and perfume don't work on Chuck. I think it actually works, but he stores all the horniness and sexual frustration under his absolute control up until he lets it all go. the fact that they tested the perfume on him might make it worst for his next victim