JManM
I've always liked the idea that they're a projection and Eidolon is responsible for them. So to kill Eidolon is to end the Endbringers. Also, let's you go after the idiots of Cauldron and look like the good guy when all the evil that the PRT's backers are responsible for comes to light. Can kill a bunch of heroes and be called the true hero when everything is said and done.