Enjoyed reading through this one a lot. The theme is very inventive and the lore/introduction is very cleanly-written. That, along with the large variety of prompts in each scene description, both feel like they'd make it MUCH easier for the DM to prep and run. The only things I'd personally change are some slight re-ordering of mechanics to make it flow a little better. For instance I feel like the Fae powers section would have been better located in the 'Attacks by Fae adversary's section even if it is right afterwards. That said, flowing from that, I did also like the different conditions, it adds a nice little mechanical wrinkle to the Havoc Engine.

The theme is interesting and fun. It feels like it's a stripped down version of Havoc Engine, which would hopefully give more space for roleplay to happen organically by deemphasizing some of the mechanical bits. That is reinforced by the periodic roleplaying prompts throughout the adventure. It seems like those drop off after the adventure gets going though, maybe there's a way to thread some more together throughout the later scenes. 

I like the idea of incorporating built in resistances to the engine and how the abilities modify stats. A few things are unclear to me though: 

- Can characters die/leave the game? The Dominated and Charmed conditions seem to have gameplay/narrative impact. The Injured condition states that fey will use injuries against the player, but it doesn't directly say if anything happens to characters when they reach 5 injuries. 

- Are there any mechanical impacts behind the instruments? They seem like they're mostly for flavor, written into the narrative descriptions for special abilities, but maybe they could be improved by using the Havoc system for equipment more directly. 

I think with a stripped down version of the havoc engine, there's more room for unique character attributes. With three stats and 1 instrument, maybe think about building out idiosyncracies for the three characters in more detail. Does it make sense for all three characters to have the same stats? Maybe they have different attributes based on their strengths. With only a few stats and relatively few dice, I worry that the session would mostly be spent trying to justify why your character's action fits the one stat you're best at rather than having a greater variety of narrative opportunity if they were personalized. 

In addition to that, maybe consider increasing the number of dice associated with the stats. The game as written takes 29 successes to complete in the shortest possible path, that assumes they're not allocating successes to defending or attacking. With smaller dice pools, I could see some of the later phases being substantially longer than the earlier phases. Maybe that's an intentional part of the pacing, but it might be something to revisit either way.