Luffy holding on to Kaido while Kaido smacks him with Lightning, wind and fire attacks was fucking badass
After Kaido dodged the Gomu lightning attack Luffy knew he has to hold on to Kaido to get a hit on him, that's why he caught onto him and now has a punch strong enough to smash Onigashima, Kaido is going to get smacked so hard he'll probably remember Rocks and how he used to whack around Kaido as a youth ala Garp and Luffy
I loved that Oda said via Kaido that DF ability isn't the end of and own haki and power reign supreme, Roger remains the biggest chad of the series. But Luffy's going to take down Kaido and come closer to that peak