So this will be some details about Thresh and my thoughts about how I think could be a good way to build him. This guide is for people who are new to this champion and for those who are looking for an effective build for him.

I will give some details about the runes masteries and items, also the pros and cons, why to play this champion.

About myself... I wouldn't like to say much. I'm just a normal guy, who likes to play League of Legends, and I like to play as a support. This is my first guide, and I tried my best to help you as much as I can with one of my favourite champions.

Pros:
- Thresh has a lot of CC
- Very powerful support
- Infinite scaling, which gives you defensive and offensive stats
- Very fun to play
- Extremely versatile kit


Cons:
- Weakish earlygame (but it depends highly on your adc)
- Difficult to proc relic shield
- Q's can be hard to land
- Magic damage can still punish you hard
- You must collect souls
- With this build you'll probably have only 30% CDR
- Can be hard to master

For runes as you can see I only take defensive stats. This is because Thresh's armor is very low, and his early game is his weakest, and I want to balance that with runes. That is why I don't take scaling runes, my focus is entirely on the early game.
Later my armor will grow indefinitely because of my passive, so I don't feel like I have to worry about that.

I think the masteries I took are quite uninteresting - but a quick walkthrough:

Wanderer vs Savagery: obviously Wanderer, because you don't want to attack minions

Merciless vs Meditation: you can choose Merciless for more damage, but I like Meditation better, because it means you'll have very little mana problems.

Greenfather's Gift vs Bandit vs Dangerous Game: this is the hardest choice. All three masteries are very useful; but once again I don't feel like I need damage, so I wouldn't take Greenfather's Gift. Considering everything I think the extra gold I get from Bandit is the most useful, because I'd like to buy items as soon as I can.

Recovery vs Unyielding: I think the health-regen I can get from Recovery doesn't worth it, but Unyielding can give me some very useful extra armor and magic resist. However it is just a personal opinion.

Explorer vs Tough Skin vs Siegemaster: another hard choice. In my opiion the 2 damage Tough Skin would protect me from is not very much. Siegemaster is more interesting, especially if my lane is pushed back, but I think most of the time I need the increased mobility.

Runic Armor vs Veteran's Scars: I don't need the extra shield strenght on myself, but +50 health earlygame can be useful. But now that Face of the mountain gives a passive shield Runic Armor became much more valueable.

Insight vs Perserverance vs Fearless: Insight is very good in my opinion, but considering that my combo needs me to get close to the enemy, I feel like Fearless is a better option. Perserverance doesn't seem bad either, but I'll get health regen from relic shield too.

Swiftness vs Legendary Guardian: no question, Swiftness is better here. +3 Armor and MR per nearby enemy champions doesn't really worth it.

Grasp of the Undying vs Courage of the Colossus vs Bond of Stone: Grasp of the Undying is not really a good choice in my opinion for Thresh, it is better for toplane I think. Bond of Stone isn't bad; I used to take it before, but Courage of the Colossus is so perfect for Thresh: it gives him a shield when he needs it most: when he goes in with his Q, or tries to keep an enemy away with his E.

My summoner spells are quite common too.

Take Flash, because it is almost your only escape tool (you can escape by landing a Q on a jungle camp like Amumu, but that's pretty situational).

I prefer to take Ignite, because it gives me extra offensive abilities, also the sight it gives over an enemy can be useful too. It is better if the enemy team has massive healing, because of the griveous wounds.

Exhaust is also a good option, because it has great defense/offense possibilities, and it can make your Q's easier to land. It can be better especially if your adc doesn't need the extra damage, but needs more lockdown (e.g. Miss Fortune), and the enemy team doesn't have massive healing (like Soraka).

Take Heal if your adc didn't take it for some reason.

I. Starting items:

As a support, you have three options for starting items:

1) Ancient Coin: This used to be my favourite choice. It is still very viable, the gold and mana regen it gives you is great, but I feel it a little too risky, especially if I am against lane-dominant enemies (like Lucian).

2) Spellthief's Edge: Thresh's abilities scale with AP, so the stats aren't that bad on this items for him. But the passive requires a very aggressive playstyle (you have to hit enemy champions for the extra gold) without providing defensive stats. So unless your lane is very easy (easier than you can foresee) I don't recommend this item.

3) Relic Shield: I used to dislike this item, and I still feel like it is not very good for new players, because the passive is hard to proc. But because of the new "quests" I feel like this item is the best choice if you can get used to it, and your adc lets you proc the passive.

Now, for the fully built support items, Ancient Coin builds into Talisman of Ascension, which gives you more utility (movement speed). This is very good in general, because if you have mobility boots if you make a mistake in positioning it is very hard to escape; but Talisman of Ascension gives you a little more surviveability in these situations too. But the quest reward feels so useless.
Spellthief's Edge would build into Frost Quenn's Claim, which would give Thresh nice offensive stats. The slow of the item would make it easier to land Q's, but the lack of defensive stats makes this item worse than the other 2 in my opinion. Also, the quest reward extra movement speed on proc is not very useful imo.
Finally Relic Shield would build into Face of the Mountain, which gives you a passive shield, and an active shield, making you very hard to deal with, unless you leap into the enemy team without backup.

In conclusion, I almost always start with Relic Shield. I take a health potion with myself, so I can stay in lane longer, and I like to buy a Control Ward at the start of the game. However it is important that don't waste your Control Ward use it wisely, put it into an important bush, but be careful, don't allow the enemy to destroy it. If you expect a very hard lane, you can take 2 health pots instead of the Control Ward, but I usually confident enough to be able to play safe. Don't forget to get a Warding Totem either.

II. Early items

When you first recall, in the best case scenario you have at least 1600 gold. In that case, buy 3 items:
- upgrade your Relic Shield into Targon's Brace
- buy Boots of Speed
- buy Sightstone

If I have significantly more than 1600 gold, I buy Boots of Mobility immediately instead of Boots of Speed. If I have just a little more, I buy one or two Faerie Charm to get more mana regen, and to start to build my Redemption.

If you have less than 1600 gold, you have to give up one or more of the three items I mentioned before.
In these cases, I almost always prefer to upgrade my Relic Shield into Targon's Brace first, for the extra gold, and the possibility to finish the quest sooner.
About the rest, it really depends on each case, how I feel about it. If we are pushed back very hard, I usually prefer Boots over Sightstone, because if I need to hug my tower, then there is nothing to ward momentarily; it is more important to get back into lane faster. However, if the match is even, I buy Sightstone if I can, because vision is extremely important.

III. Core items

After my earlygame items, I get Boots of Mobility next, because it allows me to spend the most time in lane, which allows me to colect more souls.

But, depending on how much gold I have, I buy, or start to build Redemption.

So, if I have 2700 gold, that is great, I can upgrade my boots and buy Redemption immediately. If I have less, I upgrade my boots, then I usually buy (or start to build) Forbidden Idol first, then Crystalline Bracer, if I have enough gold left.

Redemption is a great item for Thresh. Forget mana problems, it gives CDR, and it has a great active.

If I have more than 2700 gold, I try to buy a Ruby Crystal, or if I can, I upgrade my Sightstone into Ruby Sightstone to put my Redemption on a lower cooldown.

IV. Next Important Items

On my next recall, I buy Ruby Sightstone, if I havent't done before.

Then I usually finish my Face of the Mountain.

There are two items worth mentioning in my opinion for your 5th item:
- Locket of the Iron Solari
- Knight's Vow

I almost always choose Locket of the Iron Solari, for two reasons:
1) I don't really need the additional armor and MS from Knight's Vow, and I don't need the extra sustain. I am ranged, so I would heal 6% of the damage my partner deals, and I would suffer 6% of the damage (s)he receives.
2) Locket of the Iron Solari gives me a huge shield instead, especially, if I consider that because I already have Redemption at this point, my shields are 10% stronger. This item can save an ally in a crucial moment of a teamfight. Lets say, you are level 15 when you buy it. Then the strength of the shield is 616, on a 72 second cooldown because of your Ruby Sightstone. On level 18 the strength of the shield is 731.5 with the same cooldown. Since there are a lot of high-burst assassins in the game right now, this item can provide a very good protection for your teammates, far better than Knight's Vow in my opinion.

V. Final Item

My last item is situationally usually. You can buy the Knight's Vow, if you want, but I have other recommendations too:

1) Abyssal Scepter: this item is good only if your team has someone who deals AP damage - like any mage or AP assassin (Ekko for example). But if you have one of those guys, this item is very good in teamfights. It also has 10% CDR, and 65 MR, which is very good for you (souls only increase your armor), and it gives you more surviveability with 300 health and extra health regen.

2) Hextech Protobelt-01: this item is has a great active. It gives you a dash on a 32 seconds cooldown (remember, you have Ruby Sightstone). The additional 300 health is also nice. It also has 10% CDR, and 60 AP, making it a very good choice.

3) Zeke's Harbinger: I rarely buy this item, because it gives more AP and Crit Chance to an Ally, but only if it is charged. Its stats aren't that great either, the +250 mana is unnecessary, +30 Armor is nice, but not much, and +50 AP is only good for offense.

4) Frozen Heart: buy this if the enemy team has a Vayne. In that case buy this as soon as you can, in some (bad) cases even before Redemption.

Passive - Damnation

This passive is great. Basically, monsters, champions, large minions, and sometimes even small minions drop a souls on death (epic monsters drop 2). If you walk towards it, you collect it, gaining +0.75 Armor and +0.75 AP. Always try to collect all souls dropped.

A very good trick is that you can use your W, Dark Passage to collect the souls too. Just throw the lantern there, and it will collect them for you. However, be careful about not to waste your mana, and don't forget that you can do other very useful things with your lantern too.

The downside of your passive is that your movements can become somewhat predictable. Your enemies might (probably will) try to harass you when you get close for a soul, so be careful. Souls are important, but staying in lane is much more important.

(Oh, yes, and bonus attack speed has only 1/4 effectiveness on you, but who cares, you are the support, you don't need attack speed.)

Q - Death Sentence/Death Leap

Range: 1100
Cost: 80 mana
Cooldown: 20/18/16/14/12 (if you hit an enemy, even a minion or monster, the cooldown is reduced by 3 seconds)


This is your main initiation tool. It has a very good range (Blitzcrank's has 975, Nautilus' is 1100 too, but his can't go through terrain), but it has a 0.5 seconds delay, which makes it relatively easy to dodge.

So I have five advices, how to land your Q:
1) Wait for a clear shot in an unwarded bush. This can happen, but it probably won't happen too much, because the enemy will use wards (if not they'll probably not be good enough to dodge your Q anyways). But it is definitely worth a try.
2) Try to use your Q over walls (or from other blindspots). Remember, the range of the ability is very good, and unlike Nautilus (who is pulled to the terrain if his hook hits terrain) you can reach a lot of targets even over thicker walls.
3) Land your Q on enemies who are under CC. If your target is slowed, rooted, stunned... etc, it becomes way easier to land your Q.
4) Target a fleeing enemy. Low-health enemies might panic and if they flee in a straight line it is easier to land a Q on them. Even if they dodge, it might give your teammate(s) enough time to catch up and get a kill anyway.
5) If not necessary (for example there is a wall between you) don't use your Q on max range. The closer your target, the easier it is ti hit it.

If you land your Q, the target is stunned for 1.5 seconds., and you deal 80/120/160/200/240 + 50% AP magic damage to it. You also pull your target towards yourself during this time. Also, you can use the second half of the ability, Death Leap.

With Death Leap you dash to your target, but you remove your stun.

There are two important things to mention here:
1) You don't have to use the second half of your ability always. I use it usually when I go in for a kill with my full combo, or if I'm absolutely sure that me and my adc can come out victorious of the situation.
2) Even if you leap, wait. Your target is stunned, there is no need to rush. If you leap in you remove the stun. Use Death Leap in the last moment for maximum effectiveness.


Lastly, you can use your Q to escape from a bad situation, if you can land it on an enemy minion (for example if you are fleeing from the jungle to a lane) or a monster (if you flee towards the jungle).

W - Dark Passage

Range: 950 (cast range); 1500 (return range); ~150 (shield radius)
Cost: 50/55/60/65/70 mana
Cooldown: 22/20.5/19/17.5/16 seconds

You throw your lantern to a target location and it remains there for 6 seconds granting sight in a small radius. As I mentioned before it also collects nearby souls for you.

The first allied champion who gets near to it gets a shield for 4 second; the strength of the shield is 60/100/140/180/220 + the total number of the souls you collected. Your allies can also click on the lantern to dash to you.
It is very important that the lantern grants a dash; so you can't save someone for example from inside of Veigar's Event Horizon.

If you move too far away from the lantern (indicated by a golden border) it returns to you, shielding you.

This ability has many uses:
- you can scout dangerous areas, because it grants vision
- you can collect souls
- you can save an ally who is in a bad position
- you can help your jungler in a gank
- if you used your Death Leap, one of your allies can follow your initiation
just to name a few, important uses.
It is also important to note that if you do nothing but throw your lantern to an ally who is about to get a kill, you still get an assist. This is a very easy way to get assists.

E - Flay

Range: 400 (on both side, 800 in total)
Cost: 60/65/70/75/80 mana
Cooldown: 9 seconds


This ability has an active and a passive.

Passively your basic attacks deal bonus damage, depending on how much time has passed since your last basic attack.
The bonus damage is number of souls collected + 80/110/140/170/200% AD.
This passive is good to harass your enemies in lane with autoattacks; and it allows you to deal infinite amounts of damage if you collect enough souls.

With the active you knock your enemies in front of you and behind you in the selected direction, and you slow them after it for 1 second. The slow amount is 20/25/30/35/40%. You also deal magic damage: 65/95/125/155/185 + 40% AP.

This ability is very good, a reliable way to defend your adc from immediate, close threats (like a Kha'Zix). It can be used offensively too: you can knock enemies under your turret, or you can interrupt their channels or escapes.

It is important to note that this ability interrupts dashes. If your enemy has a dash ability wait until (s)he wants to use it, then interrupt it, stopping their offense or escape.

You can also use this ability to slow your enemy, making it easier to land your Q.

R - The Box

Range: 450
Cost: 100 mana
Cooldown: 140/120/100 seconds


After a 0.75 seconds delay Thresh summons a box with 5 walls, lasting for 5 seconds. If an enemy champion collides with a wall, the wall breaks, dealing 250/400/550 + 100% AP magic damage, and slowing the enemy by 99% for 2 seconds.

The next enemies who hit a wall of the boy break it, but they suffer no damage, and they will be slowed for only 1 second.

Your ultimate also can be used offensively and defensively.

It is a very effective way to lock down one or even more enemies. Especially if you combine it with your Q and E - land a Q on your target, leap in, ult, then knock your target into one of the walls - it can deal a lot of damage while holding down one target. In teamfights its effectiveness is even better as it can apply a powerful slow to all 5 enemy champions.

Defensively it is a powerful disengage tool: the slow and the damage both help you and your teammates a lot to escape.

Q-E: basic offensive combo. If your enemy is close to your turret it can be used to drag him under your turret, or if you couldn't drag him under the turretm you can still knock him there. You can also wait a little before your E; if the damage from that is unnecessary, than E only when the enemy starts to escape.

Q-E-Autoattack: same as above, but instead of instantly backing after the combo, autoattack to deal even more damage

Q-R-E: lockdown combination. Leap in, then ult, then knock the enemy into one of the walls.

E-Q: it is easier to land your Q if you used your E to slow your target.

E-Q-R: same as above, but use your ult to lock down your target for a kill.

Always remember to collect as many souls as you can.
In lane your goal is to land as many Q's as you can on the enemy adc. After level 2 you unlock your Q-E combo, which can deal a decent amount of damage. Don't be afraid to leap in a for a kill, especially if the enemy you hooked is on low health and your adc can follow your initiation. However, remember that landing hooks can be hard, especially if the enemy plays safe, behind minions. Be creative, use bushes and blindspots if you can.
The other useful thing you can do is to help your jungler to gank your lane by throwing your lantern to him, so he can jump to you.
If you can, harass your enemies with some autoattacks.
After level 6 your kill pressure increases a lot; unless you are in a desperate situation (like a very dangerous gank) save your ult for a kill.

In teamfights your goal is very similar: land a Q on a priority target (landing a Q on a tank might not be very effective), leap in if your team has the upper hand, then ult, then knock the enemy team into your ult with your E.

Use your lantern to shield an ally, or to help them escape, if they initiated a bad fight.

If you want to play aggressively (and risky) you can throw your lantern on yourself before you land your Q (of course you need to be sure you can land it), so one of your allies can instantly follow your initiation. However I don't really recommend this: if you miss your Q then you put your W on cooldown unnecessarily.

Don't forget to use your items! Redemption can turn around a fight, also the shields this build has can protect your allies very effectively.

Thresh is an amazing support. I usually have a very good time playing him. However, he is not the easiest to play and definitely not easy to master; but if you do master him it's worth it. I hope I could help you with this guide.

I try to keep this guide updated.

Version 1 - 2017.02.21.
Version 2 - 2017.05.22. updated summoner spells and items.