In an interview with gaming website Euro Gamer, Rob Pardo of Blizzard said he was confused by Valve's recent move to trademark DoTA. "To us, that means that you're really taking it away from the Blizzard and Warcraft III community."

Valve is currently working on Defence of The Ancients 2 and applied for a trademark registration for the DoTA name earlier this year. But Blizzard, who released information about their own DoTA mod for Starcraft II at Blizzcon this past weekend, are not happy. "DOTA came out of the Blizzard community," said Pardo. "It just seems a really strange move to us that Valve would go off and try to exclusively trademark the term considering it's something that's been freely available to us and everyone in the Warcraft III community up to this point."

Blizzard is apparently willing to fight their corner if it comes to it: "Our response is that they don't own the term DOTA at this point," he said. "Our contention is that it should continue to be available to Blizzard and to our community."

Source: Euro Gamer via Game Politics