The Diablo III: Reaper of Souls expansion pack, which is now part of the Diablo III: Ultimate Evil Edition collection, has apparently been spotted on the Xbox Marketplace for free play. It has been speculated that the Diablo III game might have been made free as part of the Games with Gold promotion for August.
https://www.notebookcheck.net/Diablo-III-Reaper-of-Souls-randomly-turns-up-for-free-on-the-Xbox-Live-Gold-service.553026.0.html