Storyline
Urza's Legacy continues the prequel storyline started in Urza's Saga, following Urza's quest to fight Phyrexia's godlike master, Yawgmoth, and his plans to conquer his home world, Dominaria. After an attempt to manipulate time goes catastrophically wrong, Urza searches for more allies as he builds a skyship to lead the war against Phyrexia. While he is away, the people of his Tolarian Academy have to battle a Phyrexian infestation on the island itself. The story of this set is recounted in the book Time Streams.
Read more about this topic: Urza's Legacy