Lets start off with items.....and I'll outline each of their purposes.

- RoA: This is the first item you'll need to rush as Singed. In the beginning of the game, you'll need to get a Mana Crystal, which will alleviate some of the mana problems that Singed is plagued with during early game. It will also give you some HP because of his passive, Empowered Bulwark. Once you build Catalyst, you will have much more sustain in lane because of the HP/MP regeneration provided once you level up. Do note that RoA requires time to reach its maximum stats, which is why rushing it is the best thing to do. Ideally, this item should be completed by 20 minutes or less.

tl;dr - RoA will turn you into a tanky menance and give you lots of sustain in lane.

- Mercury Treads: This item is a huge no-brainer; it is the second item you build. Its a must for Singed. The CC reduction + MR it provides will be extremely helpful, especially since the 35% CC reduction the Treads provide stack with your Insanity Potion ultimate (though the CC reduction stack is addictive).

The items you will build after this point purely becomes situational. Here are the items I commonly used for Singed:

- Frozen Heart: This is a great anti-AD/AS (autoattacker) item. It provides +99 armor, +500 MP, and 20% CDR; the mana FH gives will proc your passive, which means FH will also give you a +125 HP gain. Also its debuff aura will reduce any enemy's physical attack speed (ASPD) by 20%, which will slow down the damage output of any AS-based AD damage dealers.

- Banshee Veil: This is a great item as its unique passive offers you protection against an enemy ability targeted at you. Also, it gives a bit of damage mitigation against magic damage-based abilities. Not only to mention, you gain +375 HP, +375 MP, and +50 MR, which translates to more survivability for you (you proc Empowered Bulwark with this item). If enemy abilities are giving you problems, get this first after you get RoA and Treads

- Thornmail: This is somewhat self-explanatory, but in case auto attackers become a huge problem for you, rush this.

- FoN: This is a great item on Singed. Besides giving you a great boost in your mitigation against magic damage, it also gives a LOT of HP regeneration. In fact, by this time you build this item, you should have lots and lots of HP. This means you'll add on over 50 HP5 onto your current HP regeneration, which means you can heal up faster.

- Guardian Angel: This item is mainly a "cherry on the top" item, and is usually the last item that I would get after getting my essential items. But anyways, this item is great in case you're getting intensely focused by the enemy. You basically get a second life out of this because of its unique passive. The armor and MR boost it gives is also helpful too.

- Rylai's Crystal Scepter: This is somewhat of a "controversial" item for Singed because while it does great things for Singed (more HP and AP for him), some argue that it defeats the purpose of "chasing a Singed" because of the slow this item provides. But again, it can be argued that offensively, you can slow your enemies by kiting poison onto them and catch up to them if they ever try to run away (and Fling them back to your teammates). If you do plan to get this item, get it as your 4th/5th item because your main focus as Singed is to be as tanky as possible.

tl;dr - this build emphasizes on survivability as well as building up lots of mana (and a bit of HP) to become very tanky as possible.

Build:

- Rush your poison first, reaching max rank by level 9.
- Level up your Mega Adhesive whenever you can (1 rank at level 2 or 3, another rank at level 7/8, then max it out level 10 and beyond). The increased slow with every increasing point onto Mega Adhesive will prove extremely helpful in catching up to enemies.
- Leave Fling at rank 1 because leveling it more only increases damage dealt and mana cost. Level 1 Fling will be more than enough for your trolling teamfight needs
- Level ultimate whenever it becomes available.

Strategy:

- Since Singed is a great solo top champion, be prepared to solo at top in a 1v1 or a 1v2 situation (if your team has a jungler). If done right, this is highly beneficial to Singed as he'll level up faster as well as get tons of farm.
- Singed will have mana problems early game; use your abilities wisely. Once you get RoA, you can pretty much free-farm all you want.
- Singed is not as tanky during early game, which means you'll have to be a bit careful in terms of being aggressive in lane.
- While your poison is at low ranks (levels 1-3), you won't be able to kill off an entire minion wave with one round of poison kiting, which means you'll have to have poison on for a longer duration, or last hit with your auto attack. After level (rank) 4 in poison, though, you will be able to demolish minion creeps from full to 0 with one application of your poison. Once Singed has max poison, he can pretty much free-farm all he wants, and is very hard to deny him farm unless you catch him out of position/overextending.
- Do not forget to get wards while you're farming. While you want to free-farm like crazy, you do not also want to overextend and get ganked. By getting wards, you'll know ahead of time when you're taking things a bit too far.
- During teamfights, your role is to kite the enemy with poison, dump your Mega Adhesive on targets of priority (carries/squishies), and Fling them back to your teammatees to be picked apart.
- In contrast, Mega Adhesive can be used defensively by slowing chasing enemies, which allows you to gain more distance between them. Fling can also be used defensively by throwing chasing enemies back.
- When getting chased, have your poison on and go in a zigzag motion so there'll be a better chance the enemy might run into your poison cloud. You can either deter your enemy from chasing you further or you can turn it around in your favor if they overextend.
- Try not to overextend, especially during teamfights. Your effectiveness will be severely limited if you do so.
- Use your ultimate at the right time. Offensively, you use it to charge headlong into enemy lines and do your stuff. Since you have tons of CC reduction (~60% CC reduction with Mercury Treads and ultimate on), enemies who try to CC you will basically waste it since the CC will only last 40% of its full effect. Also, it gives a boost to your defensive stats (armor, MR), which will make you tankier while you're on your ultimate. Defensively, it can be used to jack up your HP5 and MP5 to astronomical levels and allow you to regenerate HP and MP faster. It will also allow you to run faster, have tons of CC reduction, as well as have more damage mitigation than usual, which will ensure you can survive from enemies chasing your ass.

Preferred Rune setup:

- x9 Magic Pen red (+9 magic pen)
- x9 Armor Yellow (+13 Armor)
- x9 MR Blue (+13 MR)
- x3 MS Quints (+4.5% MS total)

Preferred Mastery setup:

0/21/9 (no points into dodge-associated masteries)

Summoner spells:

These combination of summoner spells will work for Singed

- Ignite/Flash
- Ignite/Ghost (what I use)
- Flash/Ghost