Hearthstone's 'year of change' begins with a twist on one of WoW's biggest expansions, and a bucket of free cards

Being set in the Warcraft universe lets Hearthstone's developers do pretty much whatever they want with familiar moments in its history, so its next expansion puts a dark spin on a critical time in World of Warcraft. Hearthstone: Cataclysm is what would've happened if the big evil dragon, Deathwing, took over WoW in 2010 and was never defeated by players.

It will be your job to fight him in an alternate universe with a bunch of new cards and characters from Hearthstone's past. The expansion...