The teleportation to Thais cross roads generally happens when a change of map occurs, and the effected player was standing on the wrong sqm. But to add to your answer, this also occurs when you stand on tentugly's ship, and the tentacles spawn on a sqm you may be standing. Additionally the same event occurs every 2 hours after server save from whereever the portal to the heart of destruction may be. Even if the portal doesn't change, you will still get the message that you were effected by strange events and TP to Thais. This particular one can be very useful if you're trying to escape a pvp situation, and it just so happens to be that the portal is currently in the city you're in. As I said this will happen every 2 hours from the second the server comes back up, so it's easy to time.