After added Artifact in 7.0, the method to upgrade Artifact item level is always the focus of attention.
The first two slots on Artifact we unlocked can inset a different kind of relics to upgrade Artifact item level, also can strengthen a small Artifact Trait. Then, how to unlock the third slot?
The progress of unlocking the third slot on Artifact almost same for different classes. The only difference is the stories and quest props. Firstly, each class needs to complete all follower missions in Class Hall before taking the quest to unlock the third slot of Artifact. Players should check the mission list because there is prompt name prefix in the list.
Secondly, to do Class Hall quests, and reward follower Troops when finished. Fighting the specified boss in Heroic 5-man dungeons then can start the unique class story to recruit follower Troops. After finished some specified follower missions and 20 World Quests, congratulations, you've completed Class Hall battle. When you getting achievement A Glorious Campaign, you have unlocked the third slot of Artifact.
An ilvl850 Artifact relic can upgrade 41 levels for an Artifact weapon, it can be seen the importance of unlocking the third slot on Artifact.