How will kids even hurt Kaido I know he will but how
In between those two events, Kaido having his wound opened early in the fight is a relevant enough injury that does not heal quickly and will allow other SNs who aren't Luffy (especially Kidd and Killer, whose ability cannot bypass defenses like Law's) to deal less significant damages to Kaido and allow Luffy to deal many significant damages to Kaido. These damages will pile up on top of his old wound opening and wear him down as they tax his healing factor.


