The Inverse Square Law of Magic
The Hero's Guild has discovered the Laws of Magic, but have released Satan from his 5000 year prison. Full of rage and pain, Satan goes on a rampage. It will take the combined might of the old directors and the new, plus all of the heroes across the septiverse to contain The Adverseary and prevent the destruction of the accessible universes.
And they may have to sacrifice one of those universes to do it.