The original DOTA is a fan made game in the Blizzard Warcraft III Map Editor. It was made using Blizzard created models, characters, maps, animations, and a Blizzard game. Like many of the other custom games that have been made in their various Map Editors, Blizzard has let the players have free reign and stayed out of interfering with them, basically, giving the players freedom to create what they want. Regardless, they were doing this with a Blizzard product. For anyone else to try to claim ownership or copyright of the newer version of a game made using Blizzard software and a Blizzard franchise is utterly ridiculous. Doubly so if "World Editor EULA requires Blizzard's prior written consent to use for any commercial purpose" is true.