A Few Opening Words

So, you've decided to play Swain, have you? I've seen plenty of different builds and I have been experimenting throughout hundreds of matches; I'm now here to share some of my experience with you. A good way of getting started is copying the build straight away, see how it feels and try to evaluate it. Do by all means experiment yourself and deviate from the build. The more games you play, the closer you'll come to find the perfect build for you.

The Theme of the Build

I struggled quite a lot between the HP, MP and AP balance with Swain. My main goal was to have a steady increase in AP but also being able to survive in the team fights. After a lot of testing I came up with this build. The goal is to maximize Swain's AP as fast as possible, as well as being able to keep him alive and giving him a mana pool large enough to sustain his ultimate for a longer period of time.

Runes

The choices of runes are pretty much the standard of any caster. Swain does not need any mana regen runes due to his passive ability Carrion Renewal so those are immediately ignored. Marks and quintessenses are the only runes which offer magic penetration so use those spots to get the magic penetration you need. One might want to get health quintessenses instead of the magic penetration one but you'll have to figure out which ones you feel most comfortable with.

Masteries

Once again, pretty standard caster specs. I've chosen to get Burning Embers instead of Presence of the Master seeing as Swain casts his spells quite frequently and, especially early game, the 10 ability power boost is quite nice.
Swain almost always wants to have the blue golem buff (I'll come back to that later in the article) so 2 points in Meditation is pretty necessary. Another thing which differs from the normal cast build is that I've taken a point in Blink of an Eye instead of Greed . Greed gives you 1 gold per 10 seconds, that's 6 gold per minute and thusly a whooping 120 gold per 20 minutes. I've never understood the need for this mastery, seeing as 120g is easily obtained from one to two creep waves.

Good Summoner Spells

This is a must-have for all Swain users in my opinion. The fact that Torment increases Ignite's damage by another 20% is huge due to Ignite dealing true damage.
A great spell for either escaping or chasing down enemy heroes.
Same with this spell. Using either this or Flash is a personal preference, but I wouldn't recommend using both because they pretty much do the same thing.
I haven't tried this spell an awful lot but Swain tends to get focused down quite quickly during the team battles and using Cleanse to escape the early nukes is a great way to surive and thusly be able to deal tons of damage a few seconds later.

Bad Summoner Spells

Your passive regains mana for you. There is no point at all to get this spell.
Your ultimate will heal you for way more than Heal can do. Keep in mind that Heal also applies a debuff on you which reduces further healing taken by 50%. This spell actually does more damage to you than good.
The main goal is to never die. Instead of picking this you can pick a summoner spell which actually prevents you from dying instead.

Swain is great either as a mid, solo or lane hero. These general tips applies to wherever you want to go.

Early Game (level 1-8)

The first thing you want to do is grab a Doran's Ring and a Health Potion. Doran's Ring will grant you the things Swain needs the most early on, HP and AP. Once at the lane you'll want to skill Nevermove as your first skill. The reason for this is that you'll be able to harrass the enemy hero quite a lot without putting yourself at danger due to Nevermove's long casting range. Keep in mind that the spell is cast from the midpoint of the circle so you can hit enemy heroes even though they're outside your original casting range. Another reason to pick Nevermove first is if they are the ones harrassing you a lot. In this case you can use Nevermove to pick off low HP creeps and stay far away from their hero.

Once you hit level 2 you'll be able to follow up your Nevermove with a Torment if you managed to land the Nevermove on their hero. If you keep last hitting creeps you'll basically be able to harrass their hero an infinite amount of times. Don't get overzealous though and start autoattacking them, just do quick hit and run tactics and perhaps one single auto attack while they're still rooted.

By level 4 you'll have Decrepify and are now able to burst out quite a lot of dps. Keep maxing Torment as your main skill because that's the spell which will give you the greatest dps output. When the enemy hero is down to about 300 hp and you've got an opportune moment, quickly Flash/Ghost towards them and launch your Q-E-W-D combo and finish them off. If they're not paying a lot of attention they'll be dead before they even realised what happened. By using Decrepify first you'll be able to slow them down a bit, thus having an easier time to land Nevermove.

The main goal is to never go back to the base until you have enough cash to at least buy the Sorcerer's Boots. As soon as you hit level 6 you'll be able to replenish your hp quite rapidly so try to stick around for as long as you can. If you're able to survive until level 6 it'll be a breeze afterwards.

Key points: Last hit a lot to keep your money coming and your mana high. Practice landing Nevermoves on your enemy and keep harrassing them.

Mid Game (level 9-13)

This is when you, or at least are about to, have aquired your boots and a Mejai's Soulstealer. If you're able to leave your lane and gank you really should do so. The more you feed your Soulstealer the more AP you'll get. The more AP you'll get the more damage Ravenous Flock will deal and thusly heal you for more, making you harder to kill.

The concept and ideas about ganking is the same as with any hero. Try to find an opportune moment together with your allies and ambush the enemy heroes. Don't be afraid to focus different targets during your gank. Remember that all of Swain's spells except Nevermove are damage over time spells so you can easily use Torment and Decrepify on one target and lock the second target down with Nevermove. Don't take this as a rule obviously, it was just a hint. If your main target won't die from the dots and your team mates, you'll obviously focus down that hero instead of trying to get the second one as well. It's of course a lot better to kill one guy than not to kill anyone at all.

During a gank your ultimate should be on all the time, especially in large team battles as it heals you during the entire fight. It's very important that you keep a close eye on your mana and won't let it drop too low. The longer you keep Ravenous Flock active, the more mana it costs per second. This is why it's great for Swain to grab the golem buff. With it he can keep his ultimate active almost indefinately, as well as lowering the cooldown for his spells.

During this time you will have picked up a Tear of the Goddess. The idea and playstyle behind this item is explained in detail under the items section.

The spell order i choose to go here is, like i said earlier, max Torment first. Put points in Decrepify until you are able to put your second point in your ultimate and afterwards max Nevermove. The reason for this is because the larger team fights will be occuring about this time and you'll really want to start maximizing your aoe spell instead of a single target spell. Increasing levels in Nevermove not only increases its damage but also lowers the cooldown of the spell.

Key points: Try to gank as much as possible to feed your Soulstealer. Keep your ultimate active for as much as your mana pool allows you to; don't empty your mana pool completely as you'll still want to be able to fire off one last Nevermove or dot.

End Game (level 14-18)

The plan for the end game is basically continuing with the plan from the mid game. The only difference is that the larger team fights will now occur more often. During these fights you want to pay extra attention to if you are hit by ignite or are getting focused down. Ignite will completely demolish Swain as it decreases your ultimate's heal by 50%. If you are dropping rapidly in health or are getting focused down, blink away quickly and wait for the Ignite to wear off. When you aren't close to any enemies you should immediately turn off your ultimate to preserve mana and then immediately turn it on again when you're back in range.

Even though you feel invincible if you're well fed, Swain is still incredibly easy to take down if focused correctly. You can be a bit more careless and risky with Swain than with other casters but keep in mind that he's not a tank with this build. This build's main purpose is to deal massive amounts of damage.

Key points: Be wary of your mana and if you have Ignite on you. Always focus down easy targets, as always during a team fight. Swain is not unkillable just because he has his ultimate active.

A great item at the start. It gives you hp, ap and a bit of mana regen which can be handy for those times when the last hits aren't going as well as they should
With these together with the rune specs, you'll have approximately 34 magic penetration (as well as your 15% from the masteries). The starting magic resistance for all heroes is 30 MR, with masteries they'll be up in 36 MR. At the early stages of the game, your magic penetration will completely negate their magic resistance.
This item is pretty situational. If the game has started calmly and the enemy team is hard to gank I would recommend getting this until later when the bigger team fights start. Mejai's Soulstealer is nevertheless a must-have for Swain because Swain will get either assists or the actual kill during any successful fight, all thanks due to swains aoe spells. A fully stacked Soulstealer gives 180 AP.
You'll want to get this quite early to start boosting Swain's mana pool but you do not want to upgrade it to an Archangel's Staff until later. The reason for this is how the items add mana permanently. During most fights, Swain will burst out his combo quite rapidly, i.e. using 3 spells within 3-4 seconds. Archangel's Staff triggers once per 3 seconds while the tear triggers twice per 6 seconds. Effectively this means that you'll get double the mana from this item during the nuking. Keep spamming your abilities on creeps when there's no danger around just to increase your mana further. Notice that activating and de-activating your ultimate does not trigger neither the staff nor the tear!
Get either the Blasting Wand or the Needlessly Large Rod first obviously, whichever you can afford during your next visit in the base. Rabadon's Deathcap is just insane due to the +30% AP boost it gives. No need to explain it further, this item will make your AP go through the roof. The Deathcap itself contributes with 202 AP thanks to its own unique passive.
It's debatable whether to get this or Rylai's Crystal Scepter. Personally I don't care a lot for the slow from Rylai's seeing as Decrepify already slows them and Nevermove actually snares them. Getting Rod of Ages this late might seem a bit weird but it only takes 10 minutes for it to have maxed out its own stats. It just takes 3 minutes for it to give more HP than Rylai's would and together with Archangel's staff it gives 80 AP plus an additional 22 AP from the mana.
By now your tear will have accumulated quite a lot of extra mana to your mana pool and it's time to convert it into an Archangel's Staff. This will increase your total AP by another 150 AP or so.

At this point in the game your inventory will be full and you'll have to decide what to replace your trusty Doran's Ring with. It all depends on what the game looks like and what you're facing. If you are getting nuked down heavily Zhonya's Hourglass will be good due to it giving ability power and taking care of the dying-issue. If the enemy team has stacked up a lot on magic resist a Void Staff is a quite easy pick. Personally i prefer to go all out insane damage and pick up the Lich Bane. The Sheen is there to temporarily replace the Doran's Ring as it's the item in the Lich Bane which contributes with the most AP (33 AP with Archangel's Staff)

This item, with Archangel's Staff, gives 91 AP which is quite a lot, but it also offers you increased movement speed and magic resist as some sweet bonuses. The real reason to get it though is its passive. If you're getting this item you're probably at the very very late part of the game, and that's when killing their respawning inhibitors is getting important. You should have about 850-950 AP by now which means your auto attacks will hit for over 1000 damage after each spell cast. If you're in their base and the main goal is to destroy a building, keep using one spell at a time and attack their building once between each spell. Besides being able to kill buildings a lot faster, it's also a nice contribution for killing the enemy heroes.

Last hitting
Swain has a wonky attack animation and he doesn't deal an awful lot of damage with his normal attacks. Becoming a successful Swain player requires a lot of last hits on the creeps to keep regaining mana. Practice the last hitting a lot as it's probably the most vital part at the early stages of the game.

Fleeing
There are two things worth mentioning about fleeing with Swain.
1: Decrepify doesn't need Swain to perform a casting animation. This means he does not have to turn around and face his targets and he can keep running all the time.
2: Use your ultimate to be able to regain a bit of hp from the enemy who's chasing you. It might not seem like a lot of hp but it's actually quite often a very deciding amount.

Nevermove
When your team is fleeing, do take the time to place a Nevermove behind you to either snare the enemy heroes or at least force them to take a small detour around the area. One thing you'll have to be wary about is that it only snares, Nevermove does not stun. This means that they can still cast spells and kill you off if you're not careful.

When entering the brush at the early stages of the game it's good to throw down a Nevermove if you think the enemy hero will stand there. Not only will it catch them by surprise but it will also allow you to safely-ish enter the brush if you want to continue the assault.

You can hit a target outside your casting range as long as the center of Nevermove is inside the casting range.

Ravenous Flock
Always turn this spell on before entering a team fight. The ultimate is still active and running even though you're getting stunned and whatnot. Because of your ulti you'll still be able to gain life and got a lot better survival rate than if you wouldn't have had it active. There's no real reason to not have it turned on as you're going to want it active a split second later anyways.

Right. That's my take on Swain so far. I apologize if the english has been poor, seeing as it's not my mother tongue. This is also my first guide I've written so any constructive feedback and/or comments about Swain in general is more than welcome =). I've thought a lot about the build and plenty of the thoughts have not been mentioned in the article because I deemed them not relevant for this specific build. Omitted discussions include items I do not use, the other summoner spells, different rune combinations etc, as that would've made the article three times as long.

I'll try to complement the article in the future with some ingame pictures. If you feel I've forgotten to mention a specific subject or want my thoughts on something, feel free to ask.

I hope the build helped at least a bit and I'll be seeing you in LoL!