I'd guess that Tuxedage is hurt the same as the gatekeeper is because he has to imagine whatever horrors he inflicts on his opponent. Doing so causes at least part of that pain (and empathy or whatever emotion is at work) in him too. He has the easier part because he uses it as a tool and his mind has one extra layer of story-telling where he can tell himself "it's all a story". But part of 'that' story is winning and if he doesn't win part of these horrors fall back to him.