The official site also has an interview with composer Brad Derrick, who talks about the challenges involved in making sure the soundtrack was new and distinct while still reminding players of the history behind the game’s title and lore. Derrick marks the title theme as the hardest part to compose (since it’s the iconic song for the whole expansion), while also seeing the transition of one theme into another depending on player activities to be vital to making a good soundtrack. Check out the full interview if you’re curious about how the tracks got made.
Source: Official Site