I was joking (mostly) about switching. While Karna has a lot of interesting personal skills and Noble Phantasms, he has a difficult personality. He's so incredibly neutral and detached from everything. I don't like that. For a master, he's an ideal servant, because he doesn't question orders and doesn't even have a personal wish, but he's not someone who's easy to play, because, due to this characteristic, he does not really have negative emotions such as hatred and jealousy. How dull is that?