User blog comment:Kaido King of the Beasts/The Fourth Haki/@comment-71.13.82.131-20150209152650

The only reason Roger was able to do so was his master of the 3 haki's and being in possession of the Straw Hat. The Hat has mystical powers that allows the holder to take advantage of the fourth haki. I hope soon we see Luffy tap into it's full power, like he did in the afro.