Triple Trouble is a large meta-event which occurs in the Bloodtide Coast, at the Firthside Vigil Waypoint.
The event requires much more coordination than other open world events, due to the non-trivial adds.
Players will be split into three seperate squads as the boss is fought at three locations simultaneously.
To join an organized group you should be on their voice comms or check the lfg about 30min before the times above.
[TT Event Wiki] [TT Achievements]