Blizzard is in full damage control mode after the internet assumed it was shutting down development on a World of Starcraft mod that violated their trademark, despite using their own in-game tool set.

FORBES: Blizzard Plays Nice, Invites World of Starcraft Creator to HQ

When I went searching for news on World of Starcraft I learned that at least for the moment the only thing close is a mod of Starcraft II being produced by fans to create, basically, a MMORPG version of Starcraft.

FORBES: 'Cube World' Brings Back the Voxel

Especially Blizzard games in the past have been open with Mod support and a friendly open system for that (see StarCraft and WarCraft III).

FORBES: 3. Auction House