The Dahaka,A creature of darkness and sand,said to be a guardian of time, created through from the darkness,pain and regrets within a person's heart and soul by a being known as the God Of Darkness and another group of celestial beings that watch over the fabric of both time and space itself

This specfic Beyonder that played a hand in the creation of The Dahaka was the Beyonder Of The Sands named Saiyo,who would have brought the Dahaka in a timeline and dimension where Remnant and Earth exists as one world with the two merged together into one

The creature's creation and it's original mission happens to coinside with the manfestion of an ancient artifact being an hourglass that is once unlocked will unleash a substance within it will corrupt anything and anyone that gets near it fueled by it along with corrupting ,this would be known as none other than The Sands Of Time

The sands were created when a woman by the name of Kaileena (Who is said to be byproduct of the gods knowns Primordial Mortals) that holds the timeline with them) was murdered on the Island of Time by the first Dahaka which would have accidentally the Sands of Time being brought into existence

And the first case known for the sands being used was within Persia by a Prince who had used and found the sands before he would have unlocked the hourglass with a dagger that can be used reverse time when being held onto and using it

The prince was one of the original Dahaka's prey because during when he tried to fix his mistake and cheated his own demise,The creature had noticed this before it would have led to the creature going out to find the prince to finish the job of taking the prince down in order to fix up the timeline, during this same time,there were more of the Dahaka being created to make it's own species to inhabit with that very dimension one of them that were born within this timeline was Phantom

Phantom was one of the few was chosen as both a Beyonder in his own right and a herald to them as The Reaper Of Soul which for them was seen as they're own assassin trained to have to go through multiple timelines and realities in order to fix any disturbances within them which runs through an entire cycle,If the Reaper Of Souls(Especially in the case for the Dahaka race)were to perish,they would ethier reincarnate into a new being to become it again or their memories, powers and skills would transfer over to whoever else is involved within it,such a case after the original Dahaka defeated by the prince on the Island Of Time and then later the abilities and memories had transferred over to Phantom's subconscious within the present but is still in control of his own thoughts, feeling and motives