Soul

A Soul is the life essence of all living beings that originate from the Heavens that make up the Mortal Kombat universe and are used for a variety of purposes within the story of the series.

Function
A soul gives life to its owner and a sense of individual identity, but within the Mortal Kombat universe they have a variety of other functions and can serve as sources of power and longevity.

As Shang Tsung has demonstrated, absorbing other's souls allows him to extend his lifespan, and while in normal circumstances this would grant him a quasi-immortality, because of the Elder God's curse, it staves off his advanced aging.

The being Ermac is comprised of thousands of souls hosted in one body and serve as the source of his telekinetic power.

Shinnok and Quan Chi's dominion over souls can be used to revive their former owners as undead Revenants, though this is limited to souls in their domain of the Netherrealm.