The Brothers' War is the 94th Magic expansion. It is expected to be released in Q4 2022 (November).
The Brothers' War is designed as an "event set", meaning that its mechanical structure is built around an event rather than a world. In this case, the set revolves around the story of the Brothers' War, a major event in Magic's timeline that was previously portrayed in the set Antiquities and various works of fiction such as the novel The Brothers' War.
Returning to a pivotal story of Dominaria's — and Magic's — history, what started as a feud between Urza and Mishra erupted into an all-out war that set into motion the future of the plane and Multiverse itself. Through the lens of Dominaria's locations, characters, and victims of the conflict, we'll see a plane-spanning conflict escalate with artifacts, giant artifact creatures, and beyond.