Not a book, but here are two GDC postmortem talks from people who worked on Diab...

Not a book, but here are two GDC postmortem talks from people who worked on Diablo 3. There are many interesting GDC talks about game development!

GDC 2013: Shout at the Devil: The Making of Diablo III https://www.youtube.com/watch?v=FG10e0-JyjY

GDC 2015: Against the Burning Hells: Diablo III's Road to Redemption with Reaper of Souls https://www.youtube.com/watch?v=bajI1oGPhog