Board Thread:Mortal Kombat X/@comment-1084762-20150120234121/@comment-422853-20150328040734

Kimarous wrote: Where the heck did this "Shinnok demon form" hooey come from? Basically what it sounds like; he turns into a demon after he loses the amulet from Bi-Han, which I believe was the only time the form was ever seen.

https://www.youtube.com/watch?v=6RB8BD8bLa4

Not sure I'd totally count on that being the final boss of this game though.