If you're a custom game creator for the original Warcraft 3 who's preparing to move your creations to the newly released "Reforged" remake, you'd better study up on the changes to the game's End User License Agreement -- specifically the acceptable use policy for custom games.
"Custom Games are and shall remain the sole and exclusive property of Blizzard," reads the section. "Without limiting the foregoing, you hereby assign to Blizzard all of your rights, title, and interest in and to all Custom Games, including but not limited to any copyrights in the content of any Custom Games."
It is likely that the motivation behind this desire to avoid a repeat of what happened with Valve's Dota 2, the sequel to a Warcraft 3 custom game called Defense of the Ancients. The original game was created in 2003 and underwent regular updates for years while its management changed hands multiple times.
Its ownership ultimately fell into the hands of a developer who was hired by Valve in 2009 to make a standalone sequel, Dota 2. Blizzard contested the trademark, but ultimately settled to let Valve have Dota 2 and rebrand its own version into Blizzard All-Stars. Blizzard's new EULA appears to be a safeguard against any future popular custom games getting away from them in a similar way.
The policy has other clauses limiting the reach of custom games as well, including a prohibition on making games for profit and on including third-party content that might violate IP rights. Unlike the ownership clause, both of these are fairly standard to most EULAs for games with player-created content, though the former effectively bars the recreation of some of the more famous Warcraft 3 mods.