It appears that Blizzard has made some noteworthy rendering changes to World of Warcraft as this massive MMORPG does no longer support the DX9 API. Instead, the team has now added full support for Microsofts latest API, DirectX 12, meaning that players can now choose between DX11 and DX12.
Source: N4G PC World of Warcraft now supports DirectX 12, does no longer support fullscreen exclusive mode