This is the final of the Scholomance trilogy and I read it in about two days (I was on leave!).  I think if you have read the previous two books - your understanding of the Scholomance world is deeper, but it’s not essential to reading this book.  Understanding the extremes of the Scholomance world certainly helps understanding of the characters’ motivations, actions and frustrations.
Again, the author works with the complexities of friendships, alliances, cliques, conspiracies.  Another layer is added - as she walks through power (its use and abuse) and hierarchies.  The impact of a single person, with and without the support of others (a few and many) gives the reader much to reflect on.
It’s not a gentle book, not a walk-in-the-park.  But I was glad to read it.

A satisfying ending to the books prior. Getting to see all of the characters you love and care about figure out the final parts of what to do next is incredibly rewarding. This book is a lot of how even if you are the most powerful, the ties and work of the community are what really makes things possible. Would happily reread. Even though it made me cry.