— An unknown voice from the mask
The Mask of the Ancients is a mysterious artifact introduced in the rebooted timeline of Killer Instinct (2013). It was originally used by an ancient Babylonian King in order to curse Spinal. It is the source of his magical powers and immortality, but it has also driven him insane and causes him to become an obedient servant of the holder. After it was lost thousands of years ago, Ultratech discovered it and used it as leverage to get Spinal to play into their hands.
The mask appears to have some level of sentience, even speaking to Spinal in one of his endings. However, it may just have been used as a mouthpiece to a higher being able to use it or has ties to it.
Thousands of years into the B.C. times, Spinal and his bandit network were secretly recruited by Kan-Ra as part of his scheme to usurp the King. However, their plot was eventually discovered by the King, and as punishment for his crimes Spinal was cursed with the Mask of the Ancients. Under the Mask's control Spinal was a slave to the King - the Mask did not prevent rebellious thoughts and free will, but it overrode any attempt to disobey commands. After many years of serivce, the King grew tired of Spinal and had him burn himself alive as a final rite of purification in penance for his crimes. Fearing karma would strike him for the cruel punishment, the King ordered Spinal's locked up corpse and the Mask thrown into the sea. However, his servants disobeyed these orders, disposing of Spinal but keeping the Mask for themselves.Spinal's connection to the Mask remained as it was passed from collector to collector, now known only as a dormant relic. Upon awakening at the bottom of the ocean Spinal began to relentlessly search for the Mask, eventually returning to his criminal roots and became a pirate to expand his field of view. After many years the Mask fell into the hands of ARIA and Ultratech, who researched and discovered a connection between the artifact and the countless legends of Spinal's seafaring attacks. They used it as leverage for entering the Killer Instinct tournament, drawing Spinal to fight.
In the ensuing events of Spinal's Arcade Mode, three non-canon endings can be achieved. In one ending Spinal destroys the Mask, gaining his freedom and returning to rest with the dead. In the second ending Spinal keeps the Mask as a trophy for his ultimate victory and continues to adventure on. In the third ending a mysterious being incapacitates Spinal, stealing his free will and declaring to have future plans for the skeletal warrior.
The true canon ending is revealed in Season 2. At the end of the Killer Instinct tournament, Ultratech held its word and bestowed the Mask unto Spinal - however, upon equipping it Spinal discovered that its power was severely waning. Someone or something had drained its energy at some point, and Spinal set off to find the perpetrator and reclaim its power back.
- In the original Killer Instinct timeline, Spinal was revived through cell regeneration experiments done by Ultratech and not the Mask of the Ancients. Later on, the Spinal present in Killer Instinct 2/Gold was an entirely different being revived by Gargos as a temporary servant. The unused endings for Spinal in the game depict him as recovering the artifact that summoned him, which resembles a golden skull similar to the Mask of the Ancients.