Included in the pack are Nash, Hall, the "Macho Man" Randy Savage, Curt Hennig, Scott Steiner, Syxx and The Giant. Most of these wrestlers are already in WWE 2K14, but this DLC specifically adds their New World Order incarnations from the mid-to-late 90s. "Hollywood" Hulk Hogan is notably absent from the NWO DLC, but that's only because his NWO persona is available in WWE 2K14 by default.
The NWO pack will set you back $9, unless you have purchased the WWE 2K14 season pass. In that case, the DLC (and the two other packs slated to follow over the next few months) are totally gratis.