Nine Princes in Amber.
Let's look at business. In any business, you want to get to the top, but there's no easy way to the top. Everyone wants to get to the top. It's a dog-eat-dog competition. He who steps on the most people wins. Yet, you can't get to the top alone. The only people who can help you are your co-workers, who might help you or betray you as they see fit. Your position depends entirely on your ability to know the strengths and weaknesses of those around you, and the cleverness of your own mind in planning gambits.
That brings us to Nine Princes in Amber (1970), by Roger Zelazny. Raw edged, sparse, and to the point, this book introduces us to Prince Corwin, a prince of Amber, the only true city in the world. Dad is missing from the throne, so whoever can take the throne gets to be king. His only help and his only enemies are all his brothers and sisters, depending on which side they were this time. I would put this book into the "sword and sorcery" genre.
Despite its almost diminutive word count, this book packs a stunning amount of world building and politics in a brutal, sometimes merciless adventure, where there is no sense of idealism or nobility. No, this book is all about POWER, how to get it, and how to keep it.
Magic here is not "magic" in the normal fantasy sense. The primary power is the ability to walk in shadow, possible alternate universes which may or may not be there before you think them up. If you go far enough, creatively enough, you find things which weren't there before. Sometimes magic is just the local rules where you are, such as Remba, where everyone can breathe the water. And sometimes magic is just not explained, as with the trumps, which allow the princes to contact each other and to teleport.
Nine Princes in Amber is a book which will never live in the academic annals as fine literature worth studying, but if I was to recommend fantasy books worth studying, this one would be on my A list. Despite everything that it does wrong, in the end, it does the most important things right.