Triptych Mask

Totem power!

The three-faced Triptych Mask (or Onyx Triptych) of Onyx Prime allows him to see things others can't: times, places, souls, and even the afterlife. The top mask, Farsight, showed visions of other places and times. The middle mask, Predator, gave Onyx immediate insight into any creature so that he can hunt it faultlessly. The bottom mask, Mournsong, allows Onyx to watch the journey of a Spark across the hidden regions of death.

Fiction

The Covenant of Primus

The Triptych Mask was given to Onyx by Primus himself. After the War of the Primes, the mortally-wounded Onyx would look through Mournsong to see where his fellow Primes have gone, but all he could see was the AllSpark. When Onyx decided to return to Primus, he chose to bring his Triptych mask with him to serve in place of Solus Prime's Creation Lathe. After Onyx had merged with the Core, Primus used the mask to scan all life in the universe as a template for the Cybertronian species. Though the results were mostly bipedal, the mask allowed for the birth of a large diversity of new Cybertronians. The Covenant of Primus

IDW Generation 1 continuity

Alpha Trion named the Onyx Triptych as one of the artifacts and weapons belonging to the Primes, along with the Enigma of Combination and the Star Saber, regarding them as "metaphors made real" that were unbeatable by 'ordinary' Cybertronians. Aphelion