Creating a clan
Players that formed a clan can invite huge numbers of players to join their clan. And every time one of the members clear a quest, there will be a small portion of Gold and Exp shared to the members of that said clan.
The clan should also have a leveling system, and every time it levels up 5 times, the "admin"(the one who created the clan) can choose from a variety of abilities and skills for their clan, he can also discuss this with his/her members from which ability or skill to choose. And once chosen, those offline will be sent a message to inform them that their clan gained a level and that said skill or ability was chosen.