Choose the same ruleset and faction as your friends before creating a World of Warcraft: Forever character. Blizzard's September 21 ruleset announcement confirms that parties, dungeons and raids cannot group across rulesets. Horde and Alliance characters also remain unable to group together.

Rulesets replace the traditional choice of an individual realm. Blizzard describes Normal, PvP and Roleplaying, with Hardcore arriving sometime after launch. Battlegrounds may include players from other rulesets, except Hardcore; that exception does not extend to dungeon and raid groups.

PvP locks your characters to one faction

Create an Alliance character in the PvP ruleset and you cannot also create a Horde character there, or vice versa. Normal, Roleplaying and Hardcore allow characters from both factions, while keeping the grouping restriction.

Blizzard also plans population-balance controls for PvP, including the possibility of temporarily limiting new characters for a faction. Agree on your faction before the group starts creating characters.

Changing rulesets usually means a new character

Players cannot freely move between rulesets. To play under a different ruleset, Blizzard says to create a new character there.

Hardcore has a specific exception: a character that dies can transfer out to another ruleset, including PvP. Collections and Legacy Points are account-wide across rulesets, with Hardcore handled separately. Progress, collections and rewards earned there can become available elsewhere; progress from outside Hardcore cannot move into it.

Online language is an account-wide setting

Preferred Online Language sits under Options, System, Languages and Social. It applies to all characters and has a 24-hour cooldown before another change.

World of Warcraft: Forever Languages and Social settings showing Preferred Online Language.
The online language preference applies across the account and has a 24-hour change cooldown.Blizzard Entertainment

Blizzard says the preference helps players encounter others using the same language. For a planned dungeon or raid group, settle the ruleset and faction first. If your group specifically wants Hardcore, wait for a confirmed opening date; this announcement does not provide one.