Please read if you are interested in grouping in a Thor Break off with guild!
Thor break off without chains:
https://www.youtube.com/watch?v=u1ickR3LZYITheir method entails standing at the specified locations and spearing Thor's tongue when it pops out as he spams his AoE attack.
I tried this earlier today, it worked just fine:
As you can see, I've been standing there for at least 3 minutes.
This is from the other safe zone:
Just watch the animation a couple times, line up your spear with his tongue's position when it comes out, then time it right. His head swings right, left, right, up; at the 'apex' of the second swing is around the time I think you should throw, and the tongue comes out far to the side during the third swing to the right. (These directions are from Thor's point of view).