A Deadly Education by Naomi Novik is on sale on multiple platforms today (but not in every country). It starts the brilliant Scholomance trilogy, so grab it if you haven't read it yet.
https://www.amazon.com/gp/product/B084L85MZ7
And the second book, The Last Graduate, is on sale on Kobo, but not elsewhere that I saw.
https://www.kobo.com/us/en/ebook/the-last-graduate-2