Blizzard’s Hearthstone servers in China melted this past week, forcing a rollback of all player data and wiping out over two days of progress. That’s not the real news, however. After the rollback, players noticed something odd: Their legendary card drops were coming in the exact same packs that they had before the rollback.
For instance, if you got a legendary — or, more unusually, two legendaries — on the fifth pack you opened before the rollback, you’d get that same result (with different exact cards) on the fifth pack after the rollback. This Reddit thread goes into great detail about the phenomenon, strengthening the notion that there’s some kind of “pity timer” or pre-determined, not-wholly-random element to pack contents.
In theory, this means that we could always know what future packs will contain a legendary; if you knew, you might base your purchasing choice over which set you want to get a legendary from. In practice, whatever determines this is probably buried deep in the code and will never be uncovered, though there is that upcoming Chinese law that will force games to disclose the odds of their for-purchase items. It kicks in May 1, so maybe we’ll all find out the real rarity system soon.