Hearthstone Adventure Announcement on July 28th at 11 PM PDT
In an email from Blizzard to the press, an invitation has been sent out to announce an announcement! The invitation seems to be more Karazhan themed than Ulduar - very much so like an invite one would receive for a magical dinner party.
The announcement will be coming out of ChinaJoy 2016, which is why the late/early time for those in the western world.
This announcement will be taking place on July 28th at 11 PM PDT and will be streamed on Twitch.tv/PlayHearthstone.