Hearthstone Patch 8036
This patch is not live yet!
A small patch has appeared on the Blizzard download servers which contains information about three upcoming card backs.
Blackrock Mountain - Possible New Hearthstone Adventure / Expansion
Speculation: We may be getting a Blackrock Mountain adventure / expansion. There is a string which points to a presale of it becoming available and buying it will reward you with a Molten Core card back. This may not be final, it could also be Blizzard just messing around with us. Keep that in mind!
If you are not familiar with Blackrock Mountain, it is a massive Mountain between Burning Steppes and Searing Gorge (Warcraft zones) which is home to Ragnaros, Elementals, the Dark Iron, and Nefarian. In World of Warcraft, it houses several instances and three raids, and the first Hearthstone adventure, Naxxramas, was based off a raid in World of Warcraft.
Read more about Blackrock Mountain on Wowpedia.
New Card Backs
Three new card backs have been datamined, but no images are present in the client at this time. It looks like Ragnaros will be an upcoming Seasonal card back, and the other two are related to achievements.
Molten Core
Reward From: License Detected
Note: purchase brm presale
Ragnaros
Reward From: Ranked Season Play
Golden Celebration
Reward From: License Detected
Note: golden celebration cardback
Historically speaking, Achievements / Rewards which trigger off a "license detection" are related to owning a game (Warlords of Draenor Collector's Edition) or ticket (BlizzCon) on your Battle.net account. We cannot say for certain how Molten Core or Golden Celebration will be obtained at this time, but Molten Core does currently point towards a content pre-sale.