Developers at Blizzard Entertainment are targeting a July release for Curse of Naxxramas; a major update to Hearthstone that adds new cards, a new game board and, for the first time, a narrative-led single player campaign.
Players can obtain thirty new cards if they play through the Naxxramas campaign mode, wherein they will come up against numerous foes such as "the oversized arachnid Maexxna, the fungal horror Loatheb, and the shambling abomination Patchwerk".
Beating these bosses will make small batches of cards "immediately available" to the player, which is a slight breakaway from Hearthstone's custom of offering new cards via purchases of random packs.
The Curse of Naxxramas campaign will be spaced over several updates, the first of which is expected to arrive in July.
"Just wanted to give everyone a head's up that we are currently targeting to release Curse of Naxxramas during the month of July," a spokesperson for Blizzard said on the company's forums.
"Unfortunately, we still have a lot of implementing and bug fixing to get through, so please stay tuned!"
Blizzard previously said the first chapter would be free, and is expected to reveal prices for the other chapters next week.
The new cards tend to be a little more elaborate than existing sets, with an emphasis on deathrattle and stealth tactics. Many of these new cards have already been revealed and are showcased below: