My review includes spoilers, of course

I was looking for a cool tier 3 to run for my dudes and the name of this one was intriguing. Combined with the fact that Jeremy Hochhalter wrote some of my favorite CCCs like Zhentarim's Lament or The Dreaming Relic.

First of all, the things I liked: Even if I didn't read the 2 other parts of the trilogy (tier 1 and tier 2), the story award is cool and new (they can be applied to the other characters who play the other modules) and they made sense. The story was also cool and I like Velvet as a bad guy. Some of my players played Raiders of the Twilight Marsh or Claws of Fury when I DMed those adventures and it felt nice to revisit that baddie.

The inclusion of a Song Dragon, something not in 5e was well thought and well done. I think she could had been a bit more integral to the story and some player boons could had been given or something.

The earthmore and the aarakocra were interesting elements and I liked having them.

The magic item is quite cool too and it made many players happy.

The things I didn't like: The first part with the skill checks didn't please me when I read it. I never really liked that idea and I still don't. The DCs for the checks were low and easy to beat and it just seemed like a waste of time. I was happy when the wizard decided that he could just use Teleport to go help the mage in danger.

The first combat with the dire trolls was fun, 5 of 'em against the party was a good fight and I managed to down the level 14 barbarian/paladin with one. It could had been a bit more diversified though.

My main issue with the module and the combat in general was the final fight. In my opinion, this wasn't playtested enough. It has ONE Green Abishai (he's not worth his CR at all) and the Adult Black Dracolich. It was nowhere near a challenge for any players I know in tier 3. I guess it could be challenging if you have 4 level 11-12 but still. I rebuilt the encounter and added a Red Abishai (as the main emyssary), a blue abishai and 4-5 white abishais. Now, it was a good and challenging encounter. The cleric even used Heal to save the paladin. Easy fights are way too common in modules but this one was far too easy as is. If your players are min/maxers with great magic items (everyone and their mothers have a Staff of the Magi now because of the seasonal unlocks), encounters should take that in consideration.

All in all, fun adventure that you need tweak to make sure your players face a good challenge.