The pressure was something unbearable for the weaker mages, and even those who were strong felt it, yet Arthur did not.
Those mages on the second floor looked shocked when seeing Arthur walk past them like a stroll in the park, going up using the stairs, reaching the third floor.
Fewer and fewer mages were on the third floor, and the more Arthur climbed, the fewer they become. The first five floors of the dungeon were the same; a high pressure would strike upon those who stepped on the floor, making it hard to walk.
It was a way of separating those who were strong from those who were not. When Arthur reached the fifth floor, the pressure was gone.
There were some mages there, including the three who were in the tenth circle. They were resting after passing through the first five floors.