A two part passive:
1. Sett will alternate punching a target with a Left Punch and a Right Punch. His Right Punch specifically will have an additional 50 attack range (does not stack with his Q range), deal an additional 5-90 AD (+50% bonus AD) and apply on-hit effects.
2. Sett’s health regeneration will become stronger for every 5% health he is missing, increasing by an additional 0.25/0.5/1/2 (based on level). Meaning, the lower he is, the stronger the regeneration will be.

Within 5 seconds of being active, Sett’s next two autos will both gain 50 bonus attack range (does not stack with Right Punch range) and will deal 10/20/30/50 AD and an additional 1% of the target’s maximum health (scaling by 1/1.5/2/2.5/3% per 100AD). He also will gain 30% bonus movement speed towards visible champions within 2000 units.

Passive: Any damage Sett takes, calculated after resistances, will be stored 100% as Grit at a maximum of 50% of his maximum health. The Grit will decay after 4 seconds if Sett is not taking any damage.
Active: When casted, he will punch a conal AoE that deals 80/100/120/140/160 (+25% of his current Grit) and an additional 20% per 100 bonus AD. Anyone in the center of the blast will receive True Damage. He will also gain a shield equivalent to the stored Grit at the time of the cast, that decays after 0.75 seconds.

Sett will grab enemy targets on either side of him and pull them towards him dealing 50/70/90/110/130 (+60% AD). If there are enemy units on both sides of Sett, they will get stunned for 1 second, otherwise they will be slowed by 50% for 0.5 seconds.

Sett will suppress an enemy champion and carry them 600 units, where he will then slam the target and cause a shockwave that extends 250 units around him. Any enemies caught within the center of the impact will take 200/300/400 (+120% bonus AD) and an additional 40/50/60% of the grabbed champions bonus health. Enemies caught outside the center of the impact can reduce the damage by up to 75% but all targets hit will be slowed by 99% for 1 second.

Before we have a look at his runes, it is important to understand what stats are valuable to Sett, and which are not.

As a juggernaut, Sett has very distinct weaknesses that can be easily abused by other champions that you will face in the top lane. You will want to choose a major rune that will maximize your ability to control the lane in order to farm and stay relevant to the team. Trade patterns of the champion you face will be major indicators on what rune you should consider.

Best for team fighting and dueling. He can stack Conqueror easily like Lethal Tempo, causing his autos and abilities to gain an additional 1.2-2.7(based on level) bonus AD per stack (14.4-32.4 bonus AD at max stacks). Once fully stacked, he will heal for 9% of the damage he deals to champions, calculated after resistances. This keystone is more favorable over Lethal Tempo if you don’t think you can upkeep autos as much.

Best for dueling other champions if you can maintain the stacks. Any basic attacks will grant stacks of Lethal Tempo, 13% attack speed per stack (capping at 78%) and upon reaching maximum stacks, gain 50 attack range. Sett can easily achieve maximum stacks which allows him to auto-attack targets easier with the extended range. Combined with Sett’s passive and Knuckle Down (Q), he can quickly become overwhelming to his target and give him the upper hand in fights.

Best when going against champions where you will absolutely have very little openings for counterplay without a junglers help. This will often be recommended versus champions that will push you under tower and try to poke you down cheesily. These champions usually have utility in their kits that allow them to kite you well or disengage from your aggression. Anytime you are energized (moving and basic attacks generate stacks up to 100), your next basic attack will heal you for 10-100(based on level) scaling on 40% of your bonus AD. Unfortunately, the healing on minions is only 20% effective vs hitting an enemy champion, but you will gain 20% movespeed for 1 second. Paired with your Knuckle Down (Q), you may have openings to run them down if they aren’t careful with their spacing.

A very niche rune to run, wouldn’t recommend taking this rune since Lethal Tempo is a better option. Since most top laners will go Bone Plating versus Sett, the minor rune will negate a decent amount of the damage you intended to cheese them with by taking Hail of Blades. A lot of the minor runes in Domination do not help you as much as the minor runes within the Precision or Resolve trees. This keystone is a purely offensive option that you have to be confident in winning every trade you take, otherwise you will have a hard time contesting anything for farm.

Best for scaling to be a damage soaker, but only when you can get procs on the opponent consistently. This keystone is recommended only if you are able to have it ready to proc on the opponent consistently. Otherwise you will be gaining nothing from it. When you enter combat with a minion or champion you will gain stacks, upon reaching 4 your next auto will deal 4% of your maximum health as bonus magic damage and heal for 2% of your maximum health. Each proc will permanently grant 5 bonus health. You would benefit from this rune against tank champions, or other melee champions you can’t upkeep autos on reliably but can get a quick couple hits on them before they disengage. Any stacks you gain from grasp will help you beef up overtime and become a massive threat for their backline with your Haymaker (W). Notably, against a majority of the tanks within the game, you will have kill potential on them before they buy Bramble Vest or Plated Steelcaps. Once they purchase those items, you will have a harder time capitalizing on any kills, but rather your focus would shift to maximizing stacks.