According to a lawsuit filed on behalf of an author who created a guidebook for playing World of Warcraft, Blizzard has been falsely issuing DMCA takedown notices.
It seems pretty straightforward to me. The man wrote a guide to WoW that does not include any copyrightable text from the game. He includes a couple of screenshots for illustration that I would argue fall squarely into “fair use” category, and, he’s made it clear that his guide is not official or that it was published by Blizzard.
I suspect that Blizzard is going to claim that any use of the trademark infringes their rights. If that were true, then movie studies could use the DMCA to remove unfavorable film reviews simply by claiming they have a trademark right. They don’t, and neither does Blizzard.