The DLC for Batman: Arkham Knight has reportedly, not been so hot thus far. This new one looks pretty substantial though, adding multiple villains this time around. Season of Infamy.will add storylines for Ra's Al Ghul, Mr. Freeze, Killer Croc and Mad Hatter
To see it outlined, take a look at this final episode of Arkham Insider which goes into what you can expect from the DLC. It goes live December 22nd.
Take a look. There is even hints that Rocksteady isn't done entirely with Batman just yet: