It wasn’t until the League of Explorers expansion released that we discovered many of the listed cards were real and intended for this expansion. Now players are speculating on the remaining cards from the leak, which have names like Dark Summoner, Sinister Cultist and Bloodaxe Ritualist that hint at a possible Old God theme. Other cards still to be revealed include Captain Scaleblade, Dark Iron Weaponsmith, and Bloodsail Swashbuckler, which may be for another pirate-themed expansion or may somehow fit the same Old God theme
Source: Reddit