It is expected that Blizzard will reveal the new upcoming Hearthstone expansion @ 23:00 PDT on July 28th.
Blizzard has sent an invite to the community stating that an event will take place on the 28th of July PDT 23:00 PDT, and will be streamed on Twitch Here. The invite mentions that the event will be “full of magic and celebration” which subtly hints there will be a reveal or special occasion coming up (Hearthstone expansion). At the end it mentions that they have an “unforgettable adventure planned” where it make it plain obvious a reveal will be taking place.
The unusual time is likely due to the reason that it has been rumored that the reveal will take place at the China’s digital expo China Joy. Hearthstone is yet to reveal an expansion on China, which is likely due to the reason the reveal will most likely be hosted in China. China is one of Hearthstone’s biggest regions and is expected to grow as it continues to grow in popularity compared to the somewhat declining NA and EU regions. This speculation came about as a Blizzpro journalist receive an email of the reveal before Blizzard revealed the invite.
— BlizzPro (@BlizzPro) July 20, 2016