Maybe it's a new secret, maybe it's not. I remember there was a clue that had people thinking Skarlet had a secret stage fatality. Folks tried to do it on Pit bottom, it may be in the Dead Pool.
Yeah, I remember that too. Here's the facebook post from Syco Collectibles:
https://www.facebook.com/sycocollectibles/posts/413199488760656
Something I should have said back when this was being discussed, is that I thought the use of the word (private) in that facebook post could be referring to in a PRIVATE MATCH only. Also it shows a picture of the the Pit Bottom stage and there is also a Kombat code that says "What lurks at the bottom of the pit?" So maybe it's not just for fighting MK1 Reptile like how many thought, since that might be a little too obvious due to that secret already being known about from the first MK.
So it might or might not be done in the Pit Bottom stage or Dead Pool. Also guys remember character move lists show the word 'varies' next to the stage fatality. This could also mean something.
Anyways I don't have the Komplete Edition (which you might need?), but someone should try to see if they discover something by meeting all the above requirements. That is play a private match online (or maybe offline for that matter), put in the Kombat code, play in a stage with a stage fatality (maybe Pit Bottom or even Flesh Pits too) and try different button sequences at different screen ranges if a characters normal stage fatality input doesn't work. You never know...