It looks like the End-User License Agreement (EULA) for Warcraft 3: Reforged gives total ownership of all custom games to Blizzard.
As reported by PC Gamer (via GamesIndustry.biz), the policy has been updated to reflect this:
"Custom Games are and shall remain the sole and exclusive property of Blizzard. 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."
GameIndustry.biz posits that this move is perhaps due to Blizzard wishing to avoid what happened with Dota 2 and Valve where ownership kept changing hands, with Blizzard finally settling to allow Valve to have the trademark ”Dota 2.”
