I don’t know why everyone is so concerned about this, its not a legal binding contract, blizzard only owns what is theirs. They cannot own your ideas or projects, they could go behind your back and trademark the idea, but are they going to do that with every map that is uploaded to their server? It would bankrupt them trademarking every possible map that was created by someone.
Map makers don’t have anything to worry about. Blizzard cannot use an EULA to strip you of your rights to the content and ideas you create even if it is with their tools. That would be the same as Game Guru stating they own your games or RPG Map Maker saying they own your games. They don’t and would never win a legal battle trying to claim ownership. If it looks like your map is gonna take off just copyright the idea and concept and blizzard is powerless to do anything.