strongholds that are terrifyingly difficult to conquer that would require multiple guild mates venturing out on a voyage to deploy troops together in a coordinated attack against a boss or formidable captain of the seas. The achievement could grant a player a title in front of it following his/her pirates name. I.e. Captain..., ... The conqueror
Sounds like the pirate storm game,plus bonus and treasure chest achievement for guild defeating npc boss together. Nice idea for here if it's doable .