According to the search results, the Mortal Kombat 1 Premium Edition includes the following items:

• The base game (Standard Edition)
• Kombat Pack 1, which includes 6 new playable characters (Omni-Man, Quan Chi, Peacemaker, Ermac, Homelander, Takeda) and 5 new Kameo characters (Tremor, Mavado, Johnny Cage, Ferra, Khameleon)
• 1-week early access to DLC characters
• Jean-Claude Van Damme skin for Johnny Cage
• 1250 Dragon Krystals (in-game currency)

Its worth noting that the Kombat Pack 1 is the only DLC included in the Premium Edition, and any additional DLCs that come out in the future will need to be purchased separately.