Hi guys, second counter guide here. Skip to the HOW HE KILLS YOU section if you don't want to hear about his skills and other basics.
I'm writing this because Singed is an incredibly powerful champion in the right hands. He doesn't bring the biggest guns on the block, but combined with his absolutely beastly tanking ability, he doesn't need the biggest gun. He doesn't need a nuclear bomb, a Desert Eagle .50 is all he needs, because you just aren't able to block his onslaught.
Also, he IS a tank. Despite being termed a 'Battle Mage', I consider him one of the stronger tanks in the game. And he really doesn't have many overt or easily exploitable weaknesses either, which makes it extra painful to fight a pro one.
This guide is intended both for newbies and higher level skill players; his tactics are going to generally be the similar despite the skill level of any given matchup. He doesn't have anything that is horrific for noobs but zzz for pros to deal with in the same way Eve does.
WHY YOU SHOULD TAKE THIS ADVICE TO HEART
When I play Singed, typical stats are something like 5-15 kills, 0-2 deaths, and 2x the assists than I have kills. Unfortunately my best rounds as Singed don't appear to be nearly the stomps I can get with a true assassin champ, so you'll have to wait and see if the feedback agrees with me on this one.
1) Poison Trail
This is Singed's main DPS mechanism. It also is his farming tool. When activated, it constantly drains his mana and he releases a purple cloud of poison behind him as he moves. Enemy units that move through the cloud receive a DoT and take damage for a few seconds.
At early levels, its not good for much more than harassing enemy champs that dive chasing your squishies as they try to run back to safety. Maxed out, it will completely kill the ranged enemy creeps in one full length sequence (8-10 secs for all dmg to be applied or so, approximately), and 80-90% kill the warrior ones.
This skill also makes chasing him down a pain in the butt, as unless you're willing to run at an angle to his retreat path, you're going to eat several applications of the poison as he's scurrying away to safety. And again, maxed out, the damage is fairly substantial, especially if you need to chase him for awhile.
This spell has a fairly large casting range, and causes Singed to toss a sticky goo pile to an area on the ground that he targets. The casting range is greater than you would think on this. Running through the goo applies a fairly substantial snare effect to your enemies for 5 seconds or so.
It also isn't positioning dependent like the poison cloud. You get a circular targetting reticule on the ground, so you can fire in a 360 degree arc wherever you want, and again it goes quite far.
This is his chasing mechanism. If you're gooed, he is either trying to delay you an extra second because his teammates are on the way, or he's about to charge and toss/poison you. Singed doesn't have a great mana pool early game (he's just fine mid and late though) and goo is expensive in terms of his mana, so it just isn't spammed. It's used strategically, so expect to be on the receiving end of some hurt if he tosses it at you.
His bread and butter damage move, and also his initiator. If he is able to close to melee range with you, he will toss you literally over his shoulder, giving you some fairly substantial damage when you land. It's not completely analogous to Tiny's toss, as I think it only damages the target that is thrown, it has no AoE component.
The important thing to keep in mind here is that it is incredibly positioning dependant.
You are going over HIS shoulder. The ideal situation for him is to be chasing you, and to be able to catch up. You're running away, he's chasing. If he catches you, you're going to end up BEHIND him, which means you are probably now in the middle of his teammates, or the creep wave, or w/e. Which means you're going to eat poison again as well.
Also, good Singed players will turn on their poison trail ability for a second as they are running out to grab you. Thus, when you are tossed, not only are you now in the middle of his whole team or a fresh creep wave, he's also comboed you into eating the DoT from his poison. Ouch. If you see Singed begin to leak purple gas and he's running straight at you, you are about to be comboed into this.
His ultimate provides him a fairly substantial across the board combat skills buff for about 30 seconds. Movespeed, attack speed, AP, it is just a great buff in general.
What is key about it is primarily the movement speed IMO. With MS 3 booties and this on, as well as his goo, he is going to be able to catch most champs. If he does, that toss/poison combo is coming, and then of course the surprise butsecks from his buddies who are about 2 seconds behind him. This also turns him into a fairly proficient sieger. Mid and late game, once he's itemized out, he should have no problem essentially soloing a tower, with only minimal distraction needed from creeps. I've just tanked the tower shots many times, especially if the tower was already damaged from other events earlier in the match.
His passive just promotes his own survivability. Grants him additional HP depending on the size of his mana pool; the higher his max mana, the more hp he gets. Whee. There is no activatable component to it, and it doesn't really contribute to anything other than making him a lot harder to kill.
HOW HE KILLS YOU
This is kind of tricky. Most of the time, he isn't really going to be doing the killing at all. What he will do is be his teams' initiator most of the time. He is AWESOME in this role because he is so tanky. He can literally walk into a group of 4-5 enemies and take the punishment long enough to grab someone, chuck them into his team, and then escape alive.
He also makes an excellent chaser though. If you escape his team, he can trigger his ult, turn on the poison, and run you down most of the time. Pro Singed players will typically be wearing the MS 3 booties to facilitate this. That + his ult to speed him + his goo to slow you = Ruh Roh.
Now, also, his damage is hardly horrible. It's just not that great, and it's just not primarily burst. It is consistant and decent though, and combine that with his proficiency at escape and general heartiness in general, it -will- add up. A toss will take deal a couple hundred damage, and each time you get poisoned that will be a bit more, but there just isn't the incredible frontloading of damage in the same way that Ryze, or Eve, or more pure assassins are capable of unloading on you.
Singed also is somewhat unique in that, while he is not really item DEPENDANT, he scales with itemization better than average. Most of the items he wants (Rod of Ages, Warmog's, Nature's Wrath, etc) are going to give him a pretty damn impressive health pool (~4kish, endgame), and beastly regeneration. He's typically going to have 3-4 pendants of regeneration as components for higher tier items, so it's completely possible to get upwards of 20 hp/sec regen on him. Yikes.
A typical Singed gank will involve him either charging you head on, or charging you from behind.
If he charges you head on, you can recognize this when he starts beelining for you and leaking his poison. You should know that you're about to be tossed, and where you are going to land.
He has great synergy with other stunners as well, because they are able to lock you down while he closes and tosses you to the teammate that just stunned you. If you are in a lane, and a squishy starts getting up into your face and tries to stun/root/cc you, expect Singed to show up at full speed about 1 second later. Ryze + Singed has netted me so many first bloods in the first minute of the game it's not even funny. Ryze opens with cage, Singed tosses you into poison, then both beat on you while you're trying to crawl slowly back to the tower. At which point he will goo you and toss you again (cooldown on toss is ~15 secs iirc). As we've already talked about his incredible durability, he isn't going to give a shit about having your tower hit him 5-6 times if he knows he can get the kill. Be EXTRA CAREFUL tower hugging against this beast.
If he comes at you from behind, his behavior will change slightly. He will likely lay a line of poison perpendicularly across your likely line of retreat, and begin auto attacking you. If you decide to run, you'll have to go through his poison, and eat a few auto attacks while you push past him.
Once you have passed him, boom. That's when the toss will come. If he opened with his toss coming at you from behind, he will end up tossing you towards safety. I see a lot of bad Singed players do this. Thus, he has to wait until the facing is correct.
A good trick to get out of this is to run parallel to that poison line he placed perpendicularly to your line of retreat. This puts Singed into a bad position. If you are going at a 90 degree angle, does he toss you or not? He only gets one shot at the opener because of the longish cooldown. If you run at that 90 degree angle, he is going to toss you and have you end up...essentially right were you were before. Which may not enable his teammates to get the kill on you.
The prime key to avoiding Singed is to be very attuned to the champ models facing. He can only toss you and have you land BEHIND him. So make sure as best as you are able that 'behind him' = 'safer for you'.
HOW TO COUNTER SINGED
To be honest, I am unaware of any 'hard counters' to Singed. This may be due to ignorance on my part, but I just don't see any truly exploitable weaknesses to him.
His health pool and regen makes harassing him a waste of mana for the most part.
He is not a good farmer, but he is also not very item dependant, so you can't attack him there either. Also, his poison trail turns into a godly farming tool mid and late game. Starting at level 4 poison trail, all Singed needs to do is run ahead of his creep wave, turn poison on, and infect every creep in the whole wave. He'll get 3-4 kills each wave doing this, and there is no way to stop it since you can't deny the creeps.
He is somewhat vulnerable to disables, but not in the sense you're probably thinking. Again, due to his durability, stunning him can effectively prevent him from comboing you, but it really isn't going to let you kill him either. And, because his DPS, while certainly solid, isn't anything to write home about, he should be a fairly low priority target. Kill the Ryze/Eve/Twitch that's made out of paper and does more dps anyway.
The best thing you can do to counter Singed is prevent him from opening on you with his combo, which will almost certainly kill you because of his teammates in the background.
You can also try to catch him alone, and if you can get him in transit, with 1-2 of your buddies, you may kill him. But, you may not, and your time is probably better spent farming rather than trying to gank him.
Ultimately though, Singed can be ignored, and I think that should be the basis of how you counter him.
He's a great tank, but not fantastic. Good sieger, but not fantastic. Great initiator, but can have problems due to positioning/other concerns. Too durable to easily burn down quickly. And, in general, just usually doesn't present a large enough of a threat.
Resist your temptation to focus him. I know he's big and scary, and spitting that poison everyplace. Ignore it. He's TRYING to get in your face and get you to attack him. If you do so, he just laughs while he soaks up your pathetic attack and his DPS buddies lay the smack down on you. Run right past him (THAT will certainly fuck up his positioning for toss) and go for the squishies. Burn 1-2 of them down, and Singed will have to start thinking about retreating. Fast.
I hope this helps somewhat. Does he have a hard counter that I have missed? Sadly, the most you can do against a pro Singed is prevent him from initiating. Happily, a Singed that can't initiate is a meh champ at best. There are better tanks out there, better dpsers, better initiators, and better chasers. The problem with him is that he is strong in many of these things simultaneously, and doesn't really stink at anything. Even his mana pool is solid, I hardly ever find myself low enough on mana where I can't do a toss/poison/goo/ult combo. Ranged DPS is literally the only 'role' I can think of that he can't perform. Shutting down his initiations is not that difficult to do once you understand exactly how they work. It gets even better when you realize that its not hard to abuse the facing thing to your advantage. If you are able to accomplish that, you've nullified most of what makes him scary in the first place. He'll be an annoyance, not a team killer.
P.S. - I haven't heard of how Zilaes plays his Singed, is it similar to this? Every Singed I've seen that I felt was really good follows essentially this template with a few tweaks to taste, but it's possible there is some other way to build him that I just haven't seen executed properly yet.