Wow. Where to begin?

On the off chance you've read Gideon the Ninth, you'll find this very similar, in that you get a group of nobles gathered in an isolated location who fight to the death to see who will inherit the crown. Just replace necromancers with psychics. Otherwise, picture Game of Thrones, but everyone's trapped on the Iron Islands and has limited armies.

Technically this book is fantasy, as it takes place in an imaginary country, and has magic. But really, this book very much reads like historical fiction. The imaginary country is based on the Caribbean, the imaginary conquerors are insert any colonial Europeans (but pictured as Norse in this book) and the magic is more like being psychic than being a witch. This book is very much for historical fiction readers as much as fantasy readers.

The quality of the writing is excellent, the moral greys are deeply examined without getting philosophical, and the setting is breathtaking and unique.