This compelling conclusion to The Bone Witch trilogy contained every piece of an iconic, unique fantasy work:

Rin Chupeco excels at writing multiple complex character relationships within this story, and giving them all attention. Tea and Fox spend a majority of this installment separated from one another, but it's still evident how Tea's concern for her brother drives her motivations.

Kalen's loyalty really is what keeps Tea strong to see her quest through, while wrestling with her own mind. Seeing Khalad and Likh's relationship grow was the real treat of this volume

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Once again, the alternating chapter perspectives provide great depth and intrigue to the story, as I spent a majority of the time wondering how can this saga possibly end happily for characters I've grown to care tremendously for. 
Perhaps my favorite aspect of The Shadow Glass is the focus on how history becomes myths and is rewritten to fit a particular agenda. Cinderella is Dead by Kalynn Baron also does a wonderful job of tying this into the main conflicts.

In the case of The Shadow Glass, I love how this ties into not just the history of asha, but also the meta narration with our bard and Tea's missing letters 

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This series and Never Tilting World has absolutely solidified Rin Chupeco as a must read author for me. The impact of their writing and support of debut authors of color is immeasurable.