With more effort than it had taken to move the slab of stone upon the crystal shard in the Shimmering Deep, Aram moved his feet, one step, two steps, three – until he stood between Death and the murloc.
Mueh’zala stopped. He shifted into a new form, a red-rimmed spectre in black, towering over all he surveyed. Aram girded himself for whatever was to come. Out of the corner of his eye, he saw Makasa, Hackle and even Drella, ready to come to his aid. He felt Murky;s hand on his shoulder, gently urging him aside. But Aram was a stone that would not budge. It might not have been bravery, he knew. It quite easily might have been northing more than paralyzing fear that kept him rooted to the spot. Still, whatever the cause, Aramar Thorne did not stir.
Ueetay no Mueh’zala swayed back and forth hypnotically before Aram. Trolls and sacrifices held their breath. Finally, the sand whispered, Not Yet, Son of Thorne. Not yet. This is not the day. That day comes. It comes. But Mueh’zala will not engage you here or now. Our battle is yet to come, yet to come...But it will come, child. It will come. And if you lose that battle, Mueh’zala feasts on all of Azeroth. All of Azeroth...
And Mueh’zala sank from view and was gone. Aram was so stunned, he didn't even see the final loa melt back into the sand. Or notice the torches brighten and the moon shine down. The whispered words, it will come. it will come, echoed in his mind.
God of Death, Father of Sleep, Son of Time, the Night's Friend
Q: Identity of mysterious jailer - is he someone that we know connected to death i.e. Argus or Helya?
A: Intended to be a mysterious new figure - not someone we've met before but an important part of the cosmology of the Warcraft universe. Applying what we know about the universe to a new place. He's a center piece villain of this expansion.