User blog comment:Kaido King of the Beasts/Chapter 878: The Dark Night Rises/@comment-24850639-20170913164208/@comment-24850639-20170913175313

Good point, haki alone didn't seem to do the trick. Katakuri also appears to have an answer to the Gatling, reforming his body around the part Luffy punched through in order to trap him. A lot of people are saying this will be a fight that causes Luffy to activate a power up, so I'm curious as to just what that might be.