https://www.pcgamer.com/world-of-warcraft-battle-for-azeroth-pre-patch-goes-live-on-july-17/

Ahead of the expansion's launch on August 14, Blizzard has just announced a date for the World of Warcraft: Battle for Azeroth pre-patch – and it's coming next week. On July 17 the patch will roll out, serving to bridge the gap between Battle for Azeroth and last year's Legion expansion. As always, it's not just tweaks and changes: there's actual gameplay stuff added as well.

This includes a new War Mode, PvP talents "and more" that's yet to be specified. According to the announcement page, War Mode "tears down boundaries and server rule-set distinctions, allowing players on any realm to decide when they want to jump into a world PvP experience full of like-minded players in the ongoing battle between Horde and Alliance."