Hi everybody,

This is my first build for an offensive Singed and I hope you like it.

I take Magic Penetration marks, so your do more damage early game. Also end game, this will make a bigger difference than AP per level runes. The dodge seals will help you survive and personally I think that this are the best seals. I choose AP per level glyphs so you get a bit more power in the end. You can choose Magic Resistance per level to be a bit more durable or Mana per level so you have less mana problems early game and your HP increases even more per level. Choose what suits you. For Quintessences I chose AP per level. With the glyphs it will give you 51 AP at lvl 18. With Rabadon's it will increase your AP with 67AP, but you can also choose Magic Penetration, Mana per level, Magic Resistance, Dodge or Movement Quintessences. Again: Choose what suits you.

I go 9/21/0. Singed has a hard time during the laning phase, because he has no ranged attacks or skills. That's why I go for the defensive masteries. I also focus a bit on dodge, so the dodge masteries are important. It will result in a total of 19% dodge. Almost 1 of 5 hits will be dodged. The 15% magic penetration is necessary to maintain your damage output.

I always start off with a Mana Crystal and 2 health potions. The Mana Crystal wil also give you 50 additional health because of his passive. The health potions are there to let you stay in your lane a bit longer. 2 potions only cost 70 gold, and give you 400 health in the beginning. That's a lot. When I go back I try to buy the Ninja Tabi. It's no problem if you can only buy boots of swiftness. As I stated earlier: Singed has a hard time during the laning phase. After you get your Ninja Tabi, buy a Catalyst the Protector. The additional health and mana will help you stay in your lane even longer, but what will really help you is it's passive. It's also a requirement to make the Rod of Ages. After this, buy a Tear of the Goddess. The mana regen is nice and the extra mana will also give you extra health. Now you build towards the Rod of Ages. The Rod of Ages gives a nice amount of AP, health and mana. The mana will give you even more health, because of Singed's passive and later it will result in a bigger AP boosts from the Archangel's Staff. Now we build towards the Rabadon's Deathcap. It will give your skills a huge damage boost. After this you buy an Archangel's Staff. Your Poison Trail should do like 200-220 dmg a sec now. A Rylai's scepter is the next item we build towards to. It gives you a nice amount of extra health and it will let your Poison Trail slow your opponent. Most of the time, this is the last item you get before the game ends. If you still have time, try to buy a Lich Bane. It will give you additional speed, AP, Magic Resistance which we still not have besides from our ultimate and again some mana. The mana results in extra health from Singed's passive and extra AP from the Archangel's staff. In the end you will have almost 800AP, almost 3.9k HP, 100+ Armor and over 65 Magic Resistance without your ultimate. because this is our last item, you want to kill your opponent quickly, or they will catch up to you and finish their build's too. The passive from Lich Bane will help you kill towers and inhibitors quickly so you can push them down on your own.
Abyssal Scepter, Force of Nature, Will of the Ancients. Abyssal Scepter will give you more Magic Resisance and a nice aura. The aura will compensate for your lost AP and this also helps your teammates. The Force of Nature gives you speed a nice health regen and great Magic Resistane. The Will of Ancients will heal you when minions er opponents walk through your Poison Trail. It also gives a nice buff to teammates.
These are some alternatives for the Lich Bane. Choose what suits you best.

Start with Fling. It helps you to get first blood. It's just for the fling effect, so you wont't level it anymore until you need to. After this, max Poison Trail as fast as possible. It will be your main source of damage. After this max your Mega Adhensive. Each level will increase it with 10%. It will help you and your team. It's also great for catching up to your opponent, so you can fling him back. Level your ult whenever you can.

For summoner spells, I take ignite and exhaust. Ignite is a must. Singed has no ranged skills, so this is will be your one and only ranged skill. You can also do great damage over time, by using ignite on an opponent who is chasing you in your Poison Trail. I choose exhaust so you can get great crowd control. You can slow opponents with Mega Adhesive in a certain area. You can mass slow opponents with your Poison Trail when you have Rylai's Scepter and now you can even slow a single target. Ghost can be great too. Some people find ghost necessary, but what you really want is that people chase you, instead of chasing people yourself. You can choose ghost if you like a more aggressive style. Because your ultimate reduces crowd control, you don't need cleanse.
Another great summoner spells for Singed:
*Fortify* can be really fun, when you just flung your opponent to your turret! Again: Singed has a hard time during the laning phase, so if you need to go back more than expected you can still defend your turret while you are at you base regaining health.
*Flash* A great spell overall.

This is it, my Singed build. This is just my way of building. I hope this will help you while playing Singed.

Good luck and have fun playing Singed!

P.S. If there are questions, just ask them, I will answer them as quickly as possible. Place them in the comment section or add me in-game.