Since 2004, World of Warcraft players have been asked to pick a faction and run with it. If you were Horde and your best friend was Alliance, your options for doing stuff in-game were practically zero, which made for a thematically strong experience, but also one that could kinda suck if family and friends were on the other side.
As Blizzard say:
For years now, many players have questioned whether the rules restricting communication and cooperation between Alliance and Horde need to be so absolute. The faction divide could keep close friends from playing together, or cause players to feel that their faction leaves them with far fewer opportunities to pursue their favorite group content. But these downsides have long been justified in order to preserve a central element of the Warcraft universe—it all began with a game titled, “Warcraft: Orcs & Humans,” right?
That’s going to change. As part of the game’s future 9.2.5 update, Blizzard will be testing the systems “for Alliance and Horde players to form premade parties together for dungeons, raids, and rated PvP”. That’s cool! It’s also a huge change to the game for those invested heavily in the lore, so it’s going to be entirely optional, and reliant on people using invites and being on friends lists:
– Players will be able to directly invite members of the opposite faction to a party if you have a BattleTag or Real ID friendship, or if you are members of a cross-faction WoW Community.
– Premade Groups in the Group Finder listings for Mythic dungeons, raids, or rated arena/RBGs will be open to applicants of both factions, though the group leader may choose to restrict the listing to same-faction applicants if they so choose.
– Guilds will remain single-faction, and random matchmade activities like Heroic dungeons, Skirmishes, or Random Battlegrounds will all remain same-faction (both because there is less faction-driven pressure around random groups, and to avoid compromising the opt-in nature of the feature by randomly placing a queuing orc in a group with a night elf).
When cross-faction players end up in a party, they’ll still technically be “unfriendly” while outdoors, but once inside a raid/dungeon, “all members will be friendly and able to assist each other in combat, trade loot, earn shared achievements, and otherwise fully cooperate the same way members of the same faction have always been able to.”
Players can read more about the specifics of the announcement here.