Kill Ping writes: “With BlizzCon 2018 now done and dusted, a new build (Build 28366) is made available for the World of Warcrafts upcoming Patch 8.1.0. The update is currently still only available on the games PTR servers but with the developers constantly making changes to the update, the World of Warcraft patch 8.1.0 is going to be live very soon”.
Source: N4G PC World of Warcraft Patch 8.1.0 PTR; Build 28366 Update