Board Thread:Mortal Kombat X/@comment-5503721-20150716031517

How do I get the final 4 Revenant skins in the game? I have Dark Empress Kitana, Dark Raiden and Revenant Sub-Zero. How do I unlock the other 4 skins? I would appreciate it if you guys could help me. And is there any other alternative ways to get the skins? 