Steel Shoulderguards

Steel Shoulderguard can be considered the must-have support item for Sett. It offers AD and health stats. every 35 seconds, you will gain a charge that lets you execute a minion at or below 50% hp. this grants equal gold for you and your closest ally.

Knight's Vow

is an item I use almost every game. This item has a unique active: a conduit which allows you to absorb 10% of pre-mitigation damage your ally would otherwise have to take.

Dead Man's Plate

is a great option for Sett. It has some armor, and HP, but most importantly, a speed passive. Whilst moving, you can stack up Momentum, which offers you a speed boost, and can be consumed with an auto attack that deals bonus damage.

Anathema's Chains

is more of a situational item. You may usually take this as a 3rd or 4th item, if you notice one particular enemy is dealing way too much damage and you gotta tank it. It also reduces your Nemesis' tenacity by 20% when you are near them and fully stacked.

Black Cleaver

is not an item I commonly take. However, in cases where you may have gotten a few kills, or are ahead in lane and feel comfy in teamfights, this item can give you solid HP and AD.

Chempunk Chainsword

is also pretty situational. If you notice the enemy has multiple sources of lifesteal/healing, you can take this item if you still want Grievous but prefer the HP and AD stats over Thornmail.

Gargoyle Stoneplate

is a pretty rare item that I hardly ever take. However, if the damage from enemies is too much burst, and armor/MR is necessary, you can take Gargoyle's to tank a lot of damage.

Redemption

Okay, okay. Hear me out on this one. I know it sounds troll with some of the stats, but it's super cheap, can be bought as 2nd or 3rd item, and heals enough to go toe-to-toe with enchanters. You can also activate it if you're dead! (which happens a lot when you throw yourself into 5 enemies)

Randuin's Omen

in general is not a common item. However, it's pretty good if some AD assassins on the enemy team have gotten fed, and are slippery too. The item's active slows down nearby enemies and passively reduces crit damage as well as reduce post-mitigation damage per cast.

Spear of Shojin

is an item I'm more likely to take if my build is more damage based and I'm ahead after lane. Not too much to say, but the item goes well with Sett, and even has a speed boost that scales with missing health.

Spirit Visage

You should definitely buy this if you have 3 or more AP enemies, and/or a very fed AP enemy. It gives a nice bonus on any healing shielding you receive if you have an ally enchanter, or maybe an Orianna/Annie mid.

Sterak's Gage

not a common item. You can build it as a 3rd or 4th item if you wanna tank up. I like the %AD bonus and the shield you receive when HP goes at/below 30%.

Warmog's Armor

Mathematically Correct Sett, anyone? JK but the item is pretty cool to take if you're in a lot of fights and can survive them. Great if you want to take a max HP build for some reason.

Sunfire Aegis

I dont take this item too often, but it has solid armor, and Bami's is always a nice bonus if you find yourself in super long teamfights. Definitely consider it if you have a lot of enemy AD.

Thornmail

This is the item you take if the enemy is healing a ton but you don't wanna take Chempunk. Why not Chempunk? Maybe it's a fed AD champ, like Darius(gross)or Yasuo(also gross) and you wanna hold them off for the damage dealers on your team while surviving it like a pro.

Abyssal Mask

Okay, super duper uber situational item and rare too. Take this if both your team and the enemy have multiple AP champs. It helps your allies by reducing MR on enemies, and increases your own, based on how many nearby enemies there are.

Vigilant Wardstone

You will be buying this item if the game is 40-50+ minutes long (aka epic lvl 18 mode). Just sell your sup item for this one as a sort of final upgrade. You don't need to get it right away, and can only be bought after completing supp quest.

Radiant Virtue

This item feels decent as a healing option. The mythic increases your max HP by a set% and heals all allies within 1200 units of you by 2.5% max health. When you apply the math, if you have 2000 HP, you receive 250 bonus hp(the 12.5%) which only ends up healing 56.25 Hp. However, it gets better as you build more HP over the course of the game.

Stridebreaker

has become somewhat of a staple mythic for me. If you have a gold advantage and can buy this without too much problem (cause it's pretty expensive), this item opens tons of opportunities for you, and multiplies your CC utility for the team.

Locket of The Iron Solari

is a good mythic if you have some squishy allies, and want to make sure they have some extra survivability with your shield and Armor/MR bonus.(you can buy this with Redemption, it gives you a shield bonus!)

Heartsteel

When Heartsteel was first released, I took this as a mythic almost every game. The only reason why was the infinite stacking HP. Now, not so much. You can take it if you have an early gold lead and it's easy for you to earn stacks in most if not all stages of the game.

Evenshroud

depends on team comp. If you have a lot of enemies with CC, you can increase the damage taken by any enemies near you for 5 whole seconds.

Iceborn Gauntlet

Not a sucky mythic. Any of your abilities can activate the slow buff. Just remember you have to auto them after. It also gives a decent damage reduction if they try to attack you within 2.5s.

Jak'Sho, The Protean

As a general rule for Sett, HP>Armor. However, if your team isn't looking so hot, and you desperately need a strong frontline, this is a viable mythic.

Goredrinker

I don't take this too often. Maybe if you have gotten fed, and feel confident enough to keep a steady lead without making ADCs ego hurt too bad it's a decent option. Please don't take it if you know the enemy is slippery. You are better off taking Stridebreaker then, and can still apply your lead. (Basically, build it if you can sustainably duel with other enemies, and it wont hurt your team in utility.)