https://www.gamespot.com/articles/wow-pre-expansion-patch-coming-this-week-ahead-of-/1100-6460435/

The next expansion for World of Warcraft is on the horizon. Battle for Azeroth is set to launch in August, but ahead of its release, Blizzard will roll out a big pre-expansion patch this week that sets the stage for the upcoming update and introduces a number of new features to the long-running MMO.

The pre-patch is scheduled to go live on Tuesday, July 17. Among other things, it implements War Mode, a new system that allows players to opt-in or out of PvP encounters. War Mode can be enabled beginning at level 20 by visiting either Orgrimmar or Stormwind, depending upon your allegiance; toggling it on will let you battle against other players in all zones, including Northshire Abbey. However, Blizzard says that Sanctuary areas will remain excluded from PvP, even if War Mode is enabled.