I felt like I was hearing a description of a roleplaying game setting. I know I'm unusually against this sort of thing, but I was kind of miffed that we sat down in the middle of the story to have a long digression about the nature of the world. It's a cool concept, don't get me wrong, but I will almost always advocate for seeing something in action rather than hearing about something. I know it's hard to show a concept as arcane as a graveyard of worlds destroyed by apocalypses (apocalypsi?) in the space of a short story. Maybe this should be a longer piece, a novel or a series, with the mystery of where they are and what's happening gradually unfolding instead of just being infodumped in the second act.
The character of Last (or Laft; I couldn't quite tell, though the former makes a lot more sense in context) also had a really, really strong player-character vibe to him. Unfortunately, it turned the story from the interesting moral dilemma of the counselor into the story of "Look at how cool Last is!" Last didn't seem to have any intriguing flaws or much of a personality beyond knowing everything. I'd rather have seen the counselor and the criminal explore the worlds on their own. They had a weird buddy-cop vibe that amused me, whereas Last was just... too competent.
I found my mind wandering to potential interesting plot hooks I could concoct to run a D&D crew through. A particularly technologically advanced plane starting to conquer the others, for instance, and set themselves up as a ruling class, creeping outward every time their current base grew too near the Shreds. Or a quest to acquire three or four pieces of MacGuffin technology/magic to construct a ship to explore the Mists and potentially save everyone. If my group still ran D&D, I would totally be writing up a setting book for this. Somewhere between Rifts and Planescape with just a hint of Wraith...