BBY/ABY is used to position items along the Star Wars Timeline. BBY refers to Before the Battle of Yavin. ABY refers to After the Battle of Yavin. The Battle of Yavin in Episode IV: A New Hope occured in 0 BBY/ABY.
Rise of the Empire
Set in the Rebellion era in the events closely connected to the destruction of the Death Star, we see the inner workings of the darker side of the galaxy. It is a wide swath of early Dark Horse Vader comics. It features an assassination attempt on Vader and Palpatine. It also tells the story of what happens to Vader when his ship spirals out of control in the Battle of Yavin.
Star Wars Legends Epic Collection: The Empire Vol. 1 is an Epic Collection trade paperback that collects Star Wars: Republic #78–80, Star Wars: Purge, Star Wars: Purge: Seconds to Die, Star Wars: Purge: The Hidden Blade, Star Wars: Purge: The Tyrant's Fist #1–2, Star Wars: Darth Vader and the Lost Command #1–5, and Star Wars: Dark Times #1–5. It was released on April 28, 2015.