The Primal Monitor Vs The Living Tribunal
From Superman Beyond, The first Monitor that created The Anti-Monitor. If you didn't read the issue, here is some quotes:
Captain Marvel:
GRAAHH...Feedback's making my skull ring, Superman! This Monitor...It's too imense to imagine! How can something be bigger than universes?
Superman:
Some kind of abstract infinite intelligence, the biggest life form I've encountered. A conscious, living void! With our entire multiverse living inside it.