Go to the Illuminati base and get another phone call instructing you to go to Seoul.
Head over to Agartha and take the portal to Seoul.
Here is the fun World Tree traversal mission. It’s fairly linear throughout. You will soon come across a person called “The Judiciary”. Start attacking and he will run away when it’s hp reaches approximately 50%. In the next phase of the World Tree or two, you will come across “The Variable”, another Templar agent.
When you run up to the Damaged Custodian, your telephone buddy tells you that the Custodians are basically “The Final boss of the internet”, so the person you are pursuing must have ungodly powers to be able to damage/disable the custodians. Upon clicking on the Custodian, you see its last vision before it turned off. In this vision, you see your target enter the portal below.
Edit: Mission Modified
I have been informed that Funcom has modified this quest a little at this point. Thanks to Arkangyal Khans for pointing this out and letting us know how to do this part in the new version.
“After you saw the Damaged Custodian’s last vision jump down and you need to travel in Agartha again. Just enter that port and on a new tree go for the farest port. If you are in the right direction you’ll earn XP and the quest Tier switches to 5/6 (Recover the Artifact).”
This will be the end of your World Tree Traversal for the time being. Head into the portal to Shambala after your prey. Note that the following section requires quite a bit of gear or very skillful play to succeed.
After zoning into the new area, you will see three enemies before you; Rhys Delacroix, The Variable, and The Judiciary. These are very tricky to defeat, especially if you are undergeared. I recommend at least full QL6 before attempting this, and you’ll still probably need a potion. Your first task is to defeat the two adds, The Variable and The Judiciary. Keep them both together as much as possible and stand right on them. Reason being, Rhys Delacroix will throw grenades at you during the fight. These grenades also damage The Variable and The Judiciary. They will two-shot these adds. So when he throws a grenade at you, back up or sidestrafe to the outside border of it, but make sure the adds stay inside the blast radius and watch their health plummet. Weather you need to use a 2nd grenade to kill them depends entirely on how much dps you’ve been putting out. Once they are dead, the tricky part begins.
Rhys Delacroix will get 2 buffs during the fight that will devastate you. One of them is a shield, the other is him casting an AoE channeled spell that is uninteruptable and will kill you as it has unlimited range. The way you ounteract this, is when he has the shield up, you need to run over to the green statue and it will remove it from him. When he is channeling the AoE spell, run to the red statue and it will interrupt him. If he has both up, go to remove the shield first, because the interrupt from red will not work if he has the shield up. A few cycles between the statues while blasting away and he will go down. Be sure to have potions ready just in case.
Now that you have recovered the artifact, it is time to head to New York to Ship the thing away, as per you phone friends instructions.