Deadline reports Ben Affleck "will work with director Zack Snyder and screenwriter Chris Terrio behind the scenes to make the film the best it can be."
The article also notes: "Affleck is doing this to be supportive of Snyder, with whom he worked well on Batman V Superman: Dawn Of Justice," and also that: "Warner Bros is still figuring out its stylistic superhero mojo, and Affleck will help."
Affleck is also co-writing, directing and starring in the upcoming standalone Batman movie.
Batman Vs. Superman has grossed $864 million, which is shy of the $900 million needed for the movie to take a profit and well shy of the magic billion dollar number WB was hoping for.
There have been a lot of rumors and controversy as of late surrounding Zack Snyder and Batman Vs. Superman ranging from comic book professionals telling Snyder FU, to The Flash losing its director, to the panic button being hit.
"Justice League" has a November 17, 2017 release directed by Zack Snyder starring Ben Affleck as Batman, Henry Cavill as Superman, Gal Gadot as Wonder Woman, Jason Momoa as Aquaman, Ezra Miller as The Flash, Ray Fisher as Cyborg, J.K. Simmons as Commissioner Gordon and Willem Dafoe in an unknown role.