If you are a member of a guild, you can create and participate in guild battle quests.
If you're a friendly guild that doesn't like fighting (i.e. has a white [#ffffff] guild color), you cannot create or participate in guild battle quests.
Guild battles are the same as Arena, except for the fact that there are no stakes and "members of the same guild are placed in the same party".
Each guild can have a maximum of 4 participants.