Very cool pointcrawl! It reminds me of classic Planescape adventures and would fit right in with the adventure anthologies Well of Worlds or Tales from the Infinite Staircase. The isometric maps are very well made and sit beautifully within the layout!
Some general feedback:
I love the idea that characters can wake and return to their bodies, but since they can do it instantly, can they just escape any dangerous situation? I was also unsure what happens when they begin dancing again. Do they return where they left off, or start over at the ritual site? Are the enemies still waiting for them? A little clarification would help.
The ending seems to come down to one DC 18 Strength check to throw the Coils at Mrepytun. What happens if it fails? Can someone else try, or can they recover the rope and keep trying? It might be nice if choices made during the adventure could improve their chances.
I was also unsure how possession works. The main rules say the body is taken and the spirit suppressed, but the final encounter says it lasts 2d4 rounds. What does the character do during that time, and what happens when it ends?