Prior to the 13.1 update, Sett was one of the Tactical Arena champions with the most buffs. This champion gains a 1-star base health boost along with the ability to deal more effectively with skill damage.
As a result, just a few days after version 13.1 was released, Sett’s purchase rate increased to 23% (3rd highest after Alistar and Ekko). This is an extremely impressive number when in version 12.23, Sett was not used by many players.
Not stopping there, Samira becoming stronger also helps Sett benefit quite a lot. At the present time, players often aim to use 4 Keys to maximize Samira’s damage. At this time, using Sett in the upper row will save a God Armor position when there is already Draven (also a Main type) in the squad.
Another factor that makes Sett so popular is that the reroll gameplay has been greatly weakened in patch 13.1. In the previous version, 1 star Sett could not withstand the damage of Yuumi, Ezreal… in the middle of the game. When these playstyles weakened and didn’t appear much anymore, Sett suddenly became an extremely good tank.
In short, getting a lot of buffs and being suitable for the current meta has helped Sett become extremely popular. If the player needs a strong front-line tank champion that can contribute in terms of damage, then Sett is an extremely suitable choice.