Thresh is a support tank initiator.
His skills are aimed at catching vulnerable heroes during the dredge from behind the backs of tanks and vanguards so that your team can already get rid of him. He is also able to hold back the onslaught of the enemy or slow down his pace.

It works best against heroes with physical damage, as well as against heroes with low mobility.

The hero is quite difficult to master, but the difficulty lies more in accuracy.
Also, his strength lies in the fact that over time he will receive more and more armor and ability power, and therefore the longer the game goes on, the more he is a problem for the enemy.

Thresh is also able to save his allies if they are caught, pulled, or your ally himself unsuccessfully entered the battle.

Heroes are pretty flexible.
He is not constrained by the obligation to collect something specific in order to be effective. (there are even crazy ones who collect damage and crits for him, but it works)

As a result, Thresh is an excellent choice in almost any game, and therefore it can be considered strong and useful in any situation.

In the description of Thresh's counter picks, it is written that the hero is vulnerable to control when approaching.
This is true, but it is also a problem for the opponent.
So heroes like: Pantheon, Braum, Alistar, Rell (You can argue, because Rell is a hero against tanks, and with our endless armor overclocking, we are a tasty morsel for her, but, unlike her, we have damage and more impressive control), Pyke, Tryndamere really don't like to fight him.

Thresh is also a nightmare for any hero without mobility.

One well-aimed hit and you send another Yuumi or Brand to the tavern.

Thresh is a hero that requires you to be accurate, cunning and quick to react.
The better all these parameters you have, the stronger Thresh is in your hands.

This hero is considered one of the most difficult supports in the game and these are not empty words. I learned to play it at a more or less decent level after quite a long period of time. For me, there is still no decent level in the game against an opponent who is more cunning and smarter than me, and I also always need to practice in other aspects.
It is also important to know what your adk has in mind, because one skill is literally only for interacting with an ally and its use is at the level of accuracy of your first skill.

Thresh is an example of a hero that doesn't have a single correct set of items.
His skills allow you to collect both items that correspond to his type (Tank), and such items that are taken by supports whose only task is to save their allies.

Locket of the Iron Solari will always come in handy and is the best item for Thresh overall. His active skill will give everyone a shield, and his passive skill will give additional protection to allies, and also there Thresh will receive a lot of defensive indicators.

Evenshroud is a pretty good solution, but compared to Locket of the Iron Solari it loses in many cases, but if there is no burst damage, then as an option it is not bad.

Shurelya's Battlesong will be a great solution in extremely rare cases. You need to be sure that you can postpone receiving protective items until later.

Randuin's Omen or Frozen Heart?
The second item for Thresh will be more useful due to mana, but if the enemy has a lot of damage from auto attacks and there are at least two heroes with crits, it is better to choose the first one.

Mercury's Treads, Force of Nature, Abyssal Mask - their purchase is justified only by the desire not to die from two mage skills. We take the last item if we have a mage in the team.

Anathema's Chains is a great choice against unstoppable heroes who really don't like control. We buy it if the midlaner or toplaner will be too strong in the future.

Winter's Approach Thresh likes this item very much, but it requires a few nuances from you.
1) You must after the first return Tear of the Goddess
2) You have to be very accurate, because you need to get 360 points to upgrade the item.

Mobility Boots I recommend collecting almost always, as it gives you the ability to move to other lanes faster. And you will gain protection from the passive skill Damnation, so Plated Steelcaps lose in this regard.

Knight's Vow and Zeke's Convergence only pick up if you're sure these bonuses are more important than your survivability. You only take the second item if you are playing with a hero that has fast attack speed or skill spam.

Redemption I always recommend to collect, because his active skill is very useful, but sometimes it is worth replacing it with an item for protection.

Mikael's Blessing This item is not picked up by 99% of supports, but it is very strong.
Pick it up if you're willing to sacrifice a survivability item for the chance to remove a stun or slow from your ally.

You are a support, which means vision on the map, protecting your main characters, controlling objects is your main task.

You don't carry this game if you're trying to steal kills.
For kills, your adc, midlaner, toplaner, jungler will still get more profit, but not you - put up with it.
Your maximum in this regard is just to deal damage.

At the beginning of the game, you do not stand still and try to prevent the enemy from getting gold.
Catch him on auto attacks - as soon as he swung, hit him once. This is easiest on ranged heroes, but melee heroes just need more practice.
Leave the lane for adc - miss 1-2 packs of creeps.
With constant pressure, you will force him to do more or kill him altogether.

There are others besides the bottom line.
You can catch the moment when running quickly to the mid and helping to kill will be more useful than standing and soaking up the experience while your adc is farming.
Killed - look at the map and think about where you can have time to go.
Forced the enemy to return to base - look for an opportunity to help others.
Nothing threatens your adc - go roam.

Follow the map and make sure that more information is available to each member of the team.
Place wards in the enemy forest, destroy enemy wards, inform about events on the map, because the jungler cannot always do this.

Sometimes you have to sacrifice yourself.
Substitute for skill, distract yourself.
Believe me, your death, if it helped, will only be approved. (But it's better not to abuse it)

First of all, the safety of other heroes.
You don't spend healing, shields, and other saving abilities on yourself if your ally needs it.

You are a support hero - fit your role.
And you will be the best.

Remember that we play mostly aggressively, which means we must either constantly punish the enemy for farming or initiate a fight by catching the enemy with the first skill Death Sentence. Try to get the second level as early as possible and let the opponents push the line in your direction, then you will be able to turn the fight in your direction, and the jungler can also come to your aid.

If you failed to kill the enemy, you will at least knock out the summoner spells ( Flash, Heal) from them, and this is very important, because then there is an additional reason to call the jungler to you.

After success, we do not slow down.
You have to push the enemy while your adc is farming.

It turned out to catch the enemy - throw Dark Passage to your ally and get another kill.

Thresh is useless unless he tries to punish or initiate fights. Playing passively you will lose to anyone.
But do not forget that everything has a measure.

There are times when you are not able to press the enemy right away, for this you are invited to use Guardian, which will reduce damage to you and your ally.

We have a passive skill Damnation. It allows us to get armor for every soul that drops from monsters and creeps. Thus, every minute we become more armored, and at the end of the game we can withstand very high damage. Also, our abilities Flay and Dark Passage increase their effectiveness for each collected soul.

Our task remains the same - we catch the enemy so that our allies would kill him, but now our duties include protecting the entire team. To do this, we have items Randuin's Omen, Locket of the Iron Solari, Frozen Heart, as well as all items in the tab Utility option.

Flay will allow you to nullify enemy initiation attempts, and your ultimate The Box will prevent you from escaping or chasing you.

Think outside the box.
Your first skill Death Sentence helps you move a long distance.
Get attracted to the crab on the river, to the forest monsters, to the creeps in the lane.

Your third skill Flay is slightly longer if you hit the enemy with an angle.

Not everyone knows that your second skill collects souls from the passive skill, and as soon as the player stands next to the Dark Passage, the Guardian rune can already work on it.

A good and strong hero requires a lot of practice and knowledge in general. I hope this guide has introduced you to Thresh, his strengths and weaknesses.

If you do not have enough information, then you may not have looked at the notes next to each of the items.