Justice League Dark synopsis:
When innocent civilians begin committing unthinkable crimes across Metropolis, Gotham City and beyond,  Batman must call upon mystical counterparts to eradicate this demonic threat to the planet. Enter Justice League Dark, reluctantly led by the Hellblazer himself, John Constantine. Like Batman, Constantine is a cunning, often cynical loner who is the best at his chosen profession – but quickly realizes the sinister forces plaguing the planet will require help from other supernatural alliances. Forming a new “league” with sorceress Zatanna, otherworldly Deadman, and Jason Blood and his powerful alter ego Etrigan the Demon, this team of Dark Arts specialists must unravel the mystery of Earth’s supernatural plague and contend with the rising, powerful villainous forces behind the siege – before it’s too late for all of mankind.