Her novels are A Song of Wraiths and Ruin and A Psalm of Storms and Silence.
At Tor.com Brown tagged five favorite SFF books where magic has a steep cost, including:
The Belles by Dhonielle ClaytonRead about another entry on the list.
On the surface, the world of The Belles is a decadent, whimsical delight where balloons deliver your mail, tiny teacup animals dance in your palm, and everyone is beautiful. As the creators of beauty, the titular Belles are the most powerful beings in this world, but below their glittering façade lies a sinister reality that questions what it really means to live in a society where beauty is king. Clayton deftly peels back the layers of her magic to show how even the most beautiful of societies are often built on the subjugation of others. The beauty the Belles create is revealed to be a form of control upon the population, and overusing their powers leads to bodily mutilation, disfiguration, and even death. Plus, despite the privilege their position affords them, a gilded cage is still a cage, and the Belles learn that all the power in the world means nothing if you aren’t free to make choices about your own life.
--Marshal Zeringue