The card back appears to be an exclusive for gamers who pre-purchase the game, so if you’re still on the fence regarding whether or not you should get the expansion, you probably should if you don’t want to miss out on it. The expansion will cost gamers $25 and can be found via Hearthstone’s in-game shop so you will need to launch the game in order to get your hands on it.
The expansion was announced earlier this month and is expected to see a release in April. It will be a slightly smaller expansion compared to Goblins vs Gnomes and will be more along the lines of the Curse of Naxxramas expansion. It will introduce 31 new cards to the game and will introduce 5 wings that players can fight their way through, with each new wing released every week to help stagger the release of the expansion.
Blizzard will also not be including a free wing like they did with Curse of Naxxramas, so if you want to get in on the expansion, you will have to either buy the entire thing or you can choose to pay to unlock each wing separately which will end up costing you a bit more.