Remember what Hearthstone was like at launch, when Blizzard's card game was all the rage? That original 240 card set is coming back in a new way to play the game as it was in 2014.
Classic Format is Blizzard giving Hearthstone the WoW Classic treatment. As detailed in a post on Battle.net, Classic Format lets you craft decks and compete using Hearthstone's original 240 cards as they were in 2014.
When Classic format launches with the patch for the next expansion (so, before the expansion content itself unlocks), your entire collection of Basic, Classic, and relevant Hall of Fame cards will be mirrored and available for deck building in the Classic format, as they were in the 1.0.0.5832 patch of June 2014 (this is after Blizzard made "a few important changes" following the March 2014 launch). All balance changes since June 2014 are reverted.
