Diablo 3′s first expansion Reaper of Souls is still a good two months away, but you can get some of the downloading out of the way right now.
According to a Battle.net post, both the Diablo 3 game launcher and Battle.net desktop app will begin downloading data for a “future patch” from today. The download is available even to those who haven’t yet pre-purchased the expansion.
The 6GB download contains assets and information for both Reaper of Souls and an upcoming patch, but is not the complete expansion – just what it is already complete. When Reaper of Souls launches on March 25 and the patch is released, you will have more data to download – but you won’t have as long to wait to start playing.
The information is encrypted – so don’t go poking around for a preview – and should make no changes to the game or Battle.net services until Reaper of Souls goes live.