Review copy provided by the publisher. Also the author is a friend, as you will find out if you read to the end and see that I am in the acknowledgments for the honestly light and easy work of being Brandon's pal.

Good news for those of you who wait until a series is complete to read it: this is the second book in a duology! So you can just pick up Catalyst and Castoff and read them together, if you haven't yet. I'm going to try not to spoiler the first book too much, which is going to leave me vague, because this is definitely my favorite kind of sequel: the kind where the consequences follow on hard and fast from the first book. Happily for those with shaky memories, there's a quick summary at the beginning of this one.

So there are airships! There are strange vast somewhat personified forces! There are people working out their relationships in the face of personal and social change! It's that lovely kind of fantasy novel that almost might be a science fiction novel in its concern with human interactions with truly alien intelligences. I love that kind. I want more of that basically always. And if it can come with airship adventures alongside the ponderings of the nature of intelligence and caring about others, even better. Very glad this is about to make it out into the world so I can talk to more people about these books.

Castoff was such a treat to read - an incredible sequel to the debut, Catalyst!

It feels like the world and characters truly came alive even beyond the level they had in Catalyst.

The cast was taken on a wild ride, and not just on the Soul. Deyeri, Mavrin, and Eyasu all grew in meaningful ways. The reality checks felt natural and fleshed out as well, and the rest of the gang (plus newly introduced actors) really helped the human development of the novel.

The world also had some (needed, in my opinion) development in Castoff. While perhaps intentionally, Catalyst had often left readers out of world mechanics, leaving me personally lost on occasion and wanting more. Castoff delivered much of that - we got to know Aelda's religious landscape and mechanics, history, and geographical depth in great and delightful detail. Increased Aspects lore was one of my personal favourite aspects (hahah...) of this sequel, as well as the truth learned of the Citadel's well-kept secrets about them! I also adored the relationship building and depth in Castoff, both platonic and romantic. Deyeri and Mavrin obviously falling apart, and Innis stepping in was *SO* well written and made my heart so very happy, along with the developments between Linn and Atera. The elaboration of Eyasu and Mavrin's relationship (even through the tensions) was wonderful, and what was even more special was getting to see how other characters perceived that to be happening - the way Linn described their connection was so heartwarming.

I do feel that there were places where I still wanted a *touch* more elaboration or clarification though - on the Incursions, for example. There were definitely some places here and there where learning more would have been, in my opinion, only an addition and not a detriment!

I really was thrilled to read Castoff, and am thrilled to leave this review. Thank you to Net Galley, Atthis Arts, and Crilly for the ARC I received for it!

4.5 stars / 5 stars