User blog comment:B214/Volume 23 discussion blog/@comment-26285797-20170329201510/@comment-30924344-20170329202640

He already has Great Red's power sleeping; coursing through his body made from Great Red's flesh which why he was able to handle Ophi's infinity power without dying in the first place. AxA we know, well one of the abilities of it is can make Issei transform into a 100 metre dragon.

A little bit of ExE's power will be shown in Volume 24.