What the players have been waiting for is the release of a new expansion from Heartshone entitled Scholomance Academy is approaching. For this reason Blizzard will start the season of launching new cards for the expansion in stages starting now until the last new card until July 30th.
The Scholomance Academy expansion will contain 135 new cards which will launch on August 7th. Blizzard also held a closed event for the pre-release of Fireside Gathering, at which event Blizzard will give all players the opportunity to open the Scholomance Academy card pack before the expansion is officially released on August 7th.
The closed Fireside Gathering pre-release event will be held on August 1st - 4th before launching the Scholomance Academy. For more information including the card announcement schedule and details regarding the 10 new Dual-Class card combinations you can see on the official Hearthstone website.
If you want to find out more information about this closed pre-release Fireside Gathering event, you can visit the post.
Source: Hearthstone official site