Adventure groups, basically, is a group of pc's that play those charactors when the rest of that group is online. This is an idea that Elf Lord used in previous worlds, I liked the idea so I'm placing this forum topic here so people can hash out play times and essentially recruit for their adventure group.
As far as rules go, that's entirely up to the group itself. Some ideas I have though, is to give your adventure group a name, like The Red Blades, or The Protectors of Thel. Also maybe name one of the group as the "leader", though this is all roleplaying. It's entirely up to you folks
