First of all, I have to say that your PDF is wonderfully organized. Everything is clean, well spaced, and easy to follow. It was genuinely a pleasure to read.
I really like the way you integrated the ingredients. Masks as a psychic way of hiding yourself from the Phantoms feels really clever, almost like a supernatural stealth ability. I also love the exploration loop and discovering what you'll encounter through the 2d6 tables. It makes me want to keep exploring the planet.
I'm not entirely convinced that having your spirit torn from your body is what I naturally imagine as a Molt, but I do appreciate the wordplay and how it fits the world's history.
I did have two small questions while reading. I had a little trouble understanding the Challenge Pool mechanic. A short example of play would probably make it click right away.
I was also a little unsure about the purpose of harmonizing with the Echoes. I understand that you're recovering relics from a lost civilization, but I'd have loved a little more explanation about what harmonizing actually represents in the fiction and why Harmonizers are uniquely able to do it.
Overall, I really enjoyed reading it. It has a great sci-fi atmosphere. 😊