Justice League Action will debut in North America with a four-part special event titled "Shazmam Slam" December 16 on Cartoon Network. After that, new episodes of the series will air Saturday mornings beginning December 24.
"In 'Shazam Slam,' the villainous Black Adam battles Batman on the Rock of Eternity and unleashes a horde of Djinn determined to turn the Earth back to its pre-human, volcanic state. Affected by the otherworldly powers of these primordial monsters, Batman becomes possessed and is turned into a giant flying Batmonster laying waste to the Hall of Justice, with only Superman capable of taking the fight to the Dark Knight. One by one, the Justice League - with the help of Shazam (voiced by Sean Astin) and The Wizard (voiced by Carl Reiner) - must hunt down and defeat each Djinn in order to yet again save the world from destruction."
Here is a clip:
Justice League Action is debuting early for United Kingdom viewers, beginning November 26 on Cartoon Network UK.