Abilities of Sett
Spell skill priority is an important winning factor for Sett. Understanding the abilities of Sett in League of Legends is another. Below you can find all the relevant information on Sett abilities. In order for item builds you should check the build for Sett.
Passive: Pit Grit
Sett's basic attacks alternate between left and right punch. Right punch is slightly stronger and faster. Sett also hates losing, gaining additional health regeneration based off of his missing health.
Knuckle Down
Sett's next two attacks deal additional damage based off of the target's max health. Sett also gains Move Speed while moving towards enemy champions.
Sett itches for a fight, gaining msamount*100% Move Speed towards enemy champions for msduration seconds.
Additionally Sett's next two Attacks deal an additional basedamage plus maxhealthdamagecalc max Health physical damage.
Haymaker
Sett passively stores damage he takes as Grit. On cast, Sett expends all stored Grit to gain a shield and punch an area, dealing true damage in the center and physical damage on the sides.
Passive: Sett stores damagestored*100% of damage taken as Grit, up to maxgrit. Grit decays quickly adrenalinestoragewindow seconds after the damage was taken.
Active: Sett consumes all Grit, gaining a shieldconversion*100% Grit consumed Shield decaying over shieldmaxduration seconds. Sett then delivers a massive punch, dealing damagecalc plus damageconversion Grit consumed true damage to enemies in the center (max f1 damage). Enemies not in the center instead take physical damage.
Facebreaker
Sett pulls in all enemies on opposite sides of him, dealing damage and stunning them. If enemies were only on one side, they are slowed instead of stunned.
Sett smashes enemies on either side of him into each other, dealing damagecalc physical damage and Slowing them by slowamount*100% for slowduration seconds. If Sett grabbed at least one enemy on each side, all enemies are Stunned for stunduration second.
The Show Stopper
Sett carries an enemy champion through the air and slams them into the ground, dealing damage and slowing all enemies near where they land.
Sett grabs an enemy champion and Suppresses them as he carries them forward, then slams them into the ground, dealing damagecalc plus maxhealthdamage*100% of the grabbed enemy's bonus Health physical damage to surrounding enemies and Slowing them by slowamount*100% for slowduration second. Enemies take less damage the further they are from where Sett lands.
FAQ on Sett
What do you max first on Sett?
Most Sett pros max out 
Knuckle Down first.