Blizzard has filed a new trademark for something called Heroes of the Storm. The applications, filed in New Zealand last week and Canada yesterday, were spotted by a fan posting as Darrowshire at the MMO Champion forums.
As Darrowshire points out, previous Blizzard DLC announcements have traditionally followed a few months after trademarks were filed for their titles. That was true of both Cataclysm and Mists of Pandaria for World of Warcraft. This year's Blizzcon is coming up on November 8th - can we expect an announcement then?
For now, speculation seems to favour the title referring to Starcraft 2 DLC, as the name echoes that of the earlier release Heart of the Swarm even though that game's final expansion, Legacy of the Void, is already confirmed. It seems unlikely that the filing relates to Diablo 3, since that game's DLC - Reaper of Souls - has already been confirmed. Nor does it seem to fit with Hearthstone, the free to play Warcraft CCG, which is an entirely digital product. The filing for Heroes of the Storm explicitly mentions physical media, whereas the Hearthstone trademark does not.
It may be the next World of Warcraft update, of course, or maybe Heroes of the Storm is just the name of Rob Pardo's prog rock band. Then we'll all look very silly.