The Predator/Prey DLC for Mortal Kombat X is officially available as a standalone purchase. The DLC was originally offered to purchasers of the 'Kombatant Pack,' which was essentially a Season Pass for a set amount of content for the game.
If you haven't had a chance to check the DLC out, the Predator/Prey Pack brings Predator to the game, along with new skins for three characters: Commando Johnny, Infrared Scorpion, and Carl Weathers as Jax.
The skins are specific to the film, Infrared Scorpion shows how the Predator sees the world, Johnny Cage does his best impression of Arnold Schwarzenegger (except he's wearing a shirt under the vest – guess his pectorals weren't big enough to fill the role), and Jax's Carl Weathers skin has Jax as Weathers. Yeah, that one really didn't require any description.