As of the 3rd of May 2019 this has been patched and is not working anymore.
This guide is for using an exploit
In the Krypt go to where the stands for the impaled heads are.
Turn right and go through the big gate and down the stairs towards Goro's lair to get the nearest checkpoint.
Quit out to the main menu. Back at the menu press A to load back into the crypt but keep holding A.
Don't let go of A when you're in control of your character instead just walk towards one of the stands still holding A. This will impale that head.
Repeat the process.
Be quick before they patch this. Good luck!
Edit, credit to RAMrod RAMpage:
Impaling 10, 20 and finally all heads opens up Shang Tsung's treasure room and two more rooms within it. It is located at the beginning of the Krypt map right behind you.
In this room you find lots of chests for 25000 Koins which each hold a Victory and an Intro for a character.
Thanks for the heads up.