The "Brothers' War" refers to a significant conflict in the lore of the Magic: The Gathering universe, primarily involving the brothers Urza and Mishra. This war was sparked by their rivalry over powerful artifacts and culminated in a devastating battle that shaped the fate of the Dominaria plane. The conflict introduced various factions, including the Phyrexians, and led to the creation of powerful machines and spells. The war's aftermath had lasting effects on the world, influencing future events and characters in the Magic: The Gathering storyline.