Did you know that there are 'Soul Stones' in Mortal Kombat lore? It's not quite the same thing as that one Infinity Stone from the Marvel Universe
Earthrealm, Edenia, Orderrealm, Chaosrealm, Netherrealm, Dreamrealm, Heaven, and Outworld — merged with Zaterra, Vaeternus, Arnyek Islands, and Osh-Tekk — are all realms within NetherRealm Studios' Mortal Kombat universe.
The Netherrealm is particularly interesting since powerful combatants from Earthrealm, Edenia, and Outworld tend to be resurrected as Revenants in the service of the Netherrealm army — selectively. Needless to say, the Netherealm bears numerous similarities to the underworld in Greek mythology.
Those that remember Mortal Kombat: Deception might remember an event where a young Shujinko assisted Ermac in locating a Soul Stone. Ermac required a Soul Stone in order to replenish his powers as they tend to wane in the Netherrealm.
According to Dominic Cianciolo, story and voice over director at NetherRealm Studios, these Soul Stones were created by those that work for the Elder Gods.
"The Soul Stones that that are in the Netherrealm were first created by the sorcerers that toiled for the Elder Gods," stated Cianciolo. "Back in the most ancient times, the sorcerers were tasked with building a network of portals that connect all realms together. But working in the Netherrealm sapped their powers. And as a result, they needed to build the Soul Stones to restore their energy as they worked in the Netherrealm."
It's hard not to imagine the Soul Stone of the six Infinity Stones from the Marvel Universe upon hearing this. However, the Soul Stones in Mortal Kombat lore take on the appearance of monolithic obelisks rather than tiny gems.
Should there ever be a Mortal Kombat and Marvel crossover (unlikely), one can imagine how Thanos would be very interested in investigating the Netherrealm's Soul Stones. Funnily enough, Thanos is a being known as a Titan, similar to Kronika in Mortal Kombat 11.
In Mortal Kombat Deception, Ermac was eventually able to locate a Soul Stone with the assistance of Shujinko. This allowed him to restore his power in preparation for his fight against Ashrah, a demon from the Netherrealm that disguises herself as a human female.
Ironically, this is the only time the Soul Stones are mentioned in Mortal Kombat. The backstory behind them gives the impression of them being important, but they hardly play any significant role.
Source: Ars Technica.