Hey guys! I'm TheGodofPoop, a once Plat 1 who is sadly now a Gold 2, and I've been playing Thresh for a good 3 seasons now. I have over 200 ranked games with him, with an overall win rate of 64.2%. I wanted to bring some of my knowledge and experience together into a guide! Please feel free to leave any thoughts or suggestions, as that will help me improve the guide as well as my own gameplay!

Thresh is an all around solid support ever since he was released. He brings massive amounts of utility to his team with every single one of his abilities--his lantern for getting teammates out of tough situations, his hook for great CC as well as an initiation tool, and his flay and box for such potent CC that either have the potential to secure kills with or without an enemy movement ability or flash. However, he takes a lot of skill to do well with. If you don't play support a lot and are looking for a champion to play when you're last pick and you're left with support, don't play Thresh. Play Thresh only when you mean it.

(See notes in the item builds section up top for most of the explanations)

A static build is a poor build; support is perhaps one of the most fluid roles in terms of itemization, as it should be. The following are explanations for each core/situational item and when to get them. Use your judgement when weighing each option and what your team needs more.
Most often you will be getting Aegis, and most often you will be upgrading that to Locket. Aegis has been the symbol of support for a long time now, and remains a top pick for buffing your team, especially against a team with heavy magic damage. Are you against a team with literally all physical damage? Fair enough, get Frozen Heart instead. However, in the 90% of the time when you get Aegis, their is an alternative upgrade, Banner of Command. Only get that if your team is lacking in magic damage (although you really won't do all that much more yourself), or has an emphasis on split pushing or seiging.

Face of the Mountain is almost a must. It builds up from the most ideal starting item, Relic Shield, and overall has plenty of benefits for a relatively low cost. Using it on the tank in a teamfight or to help a carry survive is an invaluable asset. The alternative would be going the Talisman route, but most of the time you can make do by having the buff from Righteous Glory instead.

Currently, this item is pretty OP for its cost. It has good synergy with Face, and especially in a winning position its active is invaluable. However, if you find that your team is in a losing position and is constantly just running away without really any ability to catch people out, other defensive items may be better choices.

The magic resist bonus as well as its free QSS ability on a teammate makes this very strong against magic damage, hard CC, or in particular magic damage in the form of hard CC. Especially get this if your carries are vulnerable.

Get this if the enemy team has numerous fed auto-attack reliant champions.

If, god forbid, your whole entire team is AD, you're pretty much gonna have to buy this at some point. Oh well.

Randuin's is a good late game pick if your team needs more tankiness, or if it's a better decision to be helping to focus their much-more-fed ADC rather than protecting your own. It has SOME peeling potential, but not much. Your abilities, and exhaust if you take it, are enough for peeling.

Q: Death Sentence

This is basically what defines Thresh. This is the skill which makes or breaks your plays, and is the skill which separates the good players from the best players. Maxing this by/during mid game is essential to pulling off better plays more often, as the cooldown reduction is very significant. At late game, with 20%+ CDR, your hooks, when landed, can be on a whopping 7 second cooldown.

Some tips when hooking: when you are not visible, or basically when the enemy doesn't know you're there, just aim where they are headed. Depending on the skill level of players, even when you're visible often times you can just aim as usual. However, if you try a couple of times and you notice the enemy is good at dodging, try to notice a pattern with which way he tends to move when dodging. You'll be surprised how many players have a certain tendency or habit.

One useful situation in which you can get a nice hook is when the person you are trying to hook is between you and the wall, and they are moving upwards or downwards along the wall to try and escape you. Good players will try to dodge your hook, and there is only one direction they can dodge, by moving in the opposite direction, backwards. So aim directly at them or just behind them, predicting the dodge and landing a great hook.

In lane, if the enemy laners are having an easy time dodging your hooks, the next time you go up to them to engage, walk up (you have to be close enough for this!) to them, laugh as they try and swerve from left to right in anticipation of your hook, and instead open up with a flay + box before then easily hooking or forcing a flash.

Lastly, you should face it. You're not gonna land every hook. Maybe not most hooks, even. I don't think even the pros land most hooks, especially if playing against other pros who know how to dodge. Other players can be very unpredictable at times, so expect to miss most hooks they consciously know about. The secret is to hook when they are least expecting it, and at higher elos that's really where most of the hooks that hit, hit.

W: Dark Passage

This is the skill you should max second, for its shield as well as its reduced cooldown. The ability to get teammates to safety is a lot more valuable than damage on your flay, when it comes to mid-late game. Use this ability when your jungler ganks, as well. A good combo to pull off is to put your lantern down, move towards the enemy duo, and once your jungler grabs the lantern, flash forward and flay back for a nice gank combo sure to result in at least summoners.

E: Flay

See the notes for skill order above at the top, but usually I like putting some points into this early for harass damage. This skill is an important part of your CC kit, and also your main peel spell. Use it to make it harder for enemies to get away, to fling them into your box, or to deny certain movement abilities like Corki's or Tristana's W.

R: The Box

It's a box. And it's OP. There are several things to keep in mind when using this. First, if an enemy is moving away from you, you have to be RIGHT NEXT to them, like literally almost on top of them in order for the spell to hit, if they keep moving. Sometimes, however, in engages bot lane for example, you can put the box up but the enemy will stay INSIDE and not take damage from it, potentially winning the fight. In those types of situations, it is better to save your Flay until AFTER you box, so that you can fling them into the slow + insane damage. This also prevents them from flashing over the box to avoid damage.

EARLY

Harass, harass, harass. Every time the ADC goes in for CS, time your auto and hit him to punish him for going in. There are certain situations, however, where doing so could put your life at risk, for example if they have a support with heavy CC, or if they have a support who can do loads of damage to you when you try and harass. Regardless, wait for good hook opportunities, and feel free to play some mind games with them!

MID

If your lane starts to get ahead, start roaming with your Mobility Boots. Right after you back is a great time to do so, as the enemy has no idea whether you're going back to lane or roaming. Roaming mid and ganking with your jungler is a solid strategy, as Thresh has a lot of gank potential.

Ward a lot, clear as many wards as you can. Have vision control around dragon area, and be prepared to defend dragon, do dragon if you get a kill bot, or possibly steal it with your hook (just don't die trying). Always stay with a teammate and help them out, or be prepared to help them out of a tough situation.

LATE

This is where the teamfighting determines the outcome of the game. You have two options, one of which is probably the more appealing: hook anyone, go into their whole team, unleash your whole combo, and then die. I used to think landing your box on everyone on the other team was solid, even if you died, but most of the time, this isn't very smart. Unless you hook a valuable carry on the other team and your team needs your CC to lock down and kill that target, you should be peeling your carries until they don't have any skin left. ESPECIALLY if they have an assassin or diver who can wipe out your carries easily. Don't forget to use your actives on your items when needed, and your ignite or exhaust on the right target.

What really helps is if you catch people out with your hook. A sudden hook on an out-of-position enemy carry can be a game changer. Constantly look for those opportunities.

needless to say, is a must.

The other two options are Ignite and Exhaust. Pick Ignite if their ADC has mobility (so therefore Exhaust wouldn't help secure a kill, against Lucian especially Exhaust is useless since his dash removes it), if they have someone like Dr. Mundo or high healing power like Soraka, or if simply Exhaust isn't needed if there is no threatening assassin. With that being said, take Exhaust if your bot lane pair can't win a fight against the enemy pair without it, like if their ADC does a lot of burst damage.

A big thanks for checking out this guide, it would really help if you gave it a thumbs up (or even a thumbs down, just let me know of your opinion :D) and commented any suggestions you have! Best of luck Threshing your way to victory!