Bulletin Board is where you can play with others using Room Creation and Search. You can take on Multiplayer Quests with a maximum of 4 people. The types of Quests you can choose from will increase when your Guild Rank increases throughout the game. In Room Creation, you can create a room by selecting your required conditions, such as number of participating people and the Quest you'd like to attempt.
Guild Rank determines which Quests are available to select.
When you wish to join another player's party, you can set the conditions that suit you using Room Search. There is also a matching function that allows you to join your friends' rooms by using a room code.
Gameplay is slightly different in multiplayer. Auto-revive gems do not work and any KO’d member will simply be kicked. If the host is KO’d the game will end for all players, so be extra careful. Starting position and which enemies on the map are different too. Dramatic camera angles for EXE drive attacks are disabled.
In multiplayer since potential lag will make blocking and healing in a timely manner harder, it is recommended to avoid glass cannon builds and equip defensive gems. A healer should spam weaker heals rather than hoping to land a 100% heal right when it’s needed. Full party should be kept up at all times. Certain full party items can be very nice to use.
Multiplayer quests, especially Rank 7 and 8, often drop rare materials useful for upgrading the best equipment in the game. Your alternative is usually an uncommon boss drop, so these are far more reliable if you can get a party together.