According to a Chinese forum poster, the next Hearthstone adventure is based on a World of Warcraft raid that is three Chinese characters long.

Two days ago an entry on a Chinese forum claimed that the next hero skin would not only be Shaman, but also that it would be Morgl, and specified that it would be obtained through a then unannounced Recruit A Friend system. No one really gave it any attention though as there were no credible sources or history of leaks to back it up. But revisiting the post after the hero skin release and seeing that it was spot on has the Hearthstone community speculating as to which adventure it could possibly be.

Originally reported by CelestialSinn and further explained by a user on Reddit, the post is now receiving a lot of attention. "The next adventure is a 3-Chinese characters raid," the user says.

With that in mind the following raids have been determined by the community to be possibilities:
  • ??? Karazhan
  • ??? Ulduar
  • ??? Terrace of Endless Spring
  • ??? Highmaul
It's worth noting that adventures average 15 bosses per release and this means that unless Blizzard makes up or promotes some minor minions to boss status, it's unlikely that Terrace of the Endless Spring and Highmaul - at four and seven bosses, respectively - would be selected. And considering many WoW players cite Karazhan and Ulduar as some of the best raids to ever exist, they're far more likely in our eyes.