Honkai: Star Rail

As I understand it, the plot here is meant as chapters.

During the passage of the Swarm, you can come across encounters with Ions.

Yes, we mean 13 chapters, not difficulty levels. It is enough to pass level 3 of difficulty, and level 4 you can pass 1 part on the tasks of traces. When completing the parts, there will be text inserts with the choice of element; there you should choose options with conservation (shield) or abundance (ear). For 20 choices, each element will give 4 traces. This will be enough to close all chapters.