In the midst of the Battle of Silvermoon, a huge shadow covers the sun. Horrified, the blood elves notice a floating necropolis, Naxxramas, approaching their beloved city. This evil entity is unnatural, but there is something familiar to them. They prepare for what awaits them and ask for help. With you comes the Rise of the Lich King, Return to Naxxramas minikit!
Released internationally on February 14, Return to Naxxramas contains 38 new cards: 4 legendary cards, 1 epic card, 17 rare cards, and 16 common cards. You can get the new cards in Rise of the Lich King packs or by purchasing the full 72-card deck*. Normal versions of the minikit can only be purchased in-game for 2,000 gold or 1,500 runestones. The gold version can be purchased for $69.99 or, for the first time ever, for 10,000 gold. The gold minikit option also includes an additional legendary diamond card!
More information here.