https://www.youtube.com/watch?v=uXb4gzgvHQk
Some of the most memorable events that have occured in the history of MMO's was the sleeper in everquest, This was a boss that you had 1 shot to kill on a server (was never meant to be killed) this one even brought together major guilds on the FF PvP server to defeat it and was by far one of the most memorable moments in MMO history,
Events like these in AoC would i think go a long way and also adds an avenue for devs to put there 1 of a kinda legendary items that a server can only have 1 of at a time, realy hard one chance per server bosses that drops those one item per server legendary items.
