Well, reading it again it seemed to have relieved some of the pain... but at the same time, some time has passed. Everyone was knocked out because of the previous bomb, which should've been quite powerful.

The Yonkou = Four Emperors... the 4 Greatest Pirates that include White Beard and Shanks. We recently heard of Kaidou who if not mistaken fought with Moria (maybe the guy who destroyed his whole crew).