A clan is a tag by your name, a shared bank, and a reason to log in on an evening you weren't planning to.
Every kill pays each clanmate standing within 48 blocks of it: 97% each with two of you, easing down to 70% each once ten of you crowd round the same mob. You can found a clan from level 10 for 5,000 gold, and it holds up to twenty players. A clan is also what gets you into the daily dungeons, which are still a prototype.
Back on SweMine, every clan on the server piled into one arena for the clan war, sometimes hundreds of players at a time. It was massive, and it's coming back. Twice a week the gates of Dustos open and the oath is suspended for an hour: clan against clan, all fighting for the last hit on a King who gets tougher the more players are online.
He doesn't just stand there, either. The King fights back in three phases, with slams and sweeps you can see coming, shards falling from above and his royal guards at his side.
The clan that lands it takes the crown. A tenth of the gold everyone earns in the zones piles up in the crown's holdings, along with a cut of every auction-house sale, and the crown holds the only key to the Abyss. It's back on the line at every Oathbreak, and if the King outlasts the hour, the crown lies vacant.