Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Passive: Empowered Bulwark - Increases Singed's health by .25 for each mana point he has.
Q: Poison Trail - Toggle: Singed lays a poisonous trail which deals 22 / 34 / 46 / 58 / 70 (+30% of ability power) magic damage per second.
W: Mega Adhesive - Singed throws a vial of mega adhesive on the ground causing all enemies who touch it to be slowed by 35 / 45 / 55 / 65 / 75% for 5 seconds.
E: Fling - Singed flings an enemy over his shoulder, dealing 100 / 150 / 200 / 250 / 300 (+100% of ability power) magic damage and slowing the enemy when they land.
Ultimate: Insanity Potion - Singed drinks a potent brew of chemicals, granting him 35 / 50 / 65 enhanced damage, attack speed %, ability power, armor, movement speed, and regeneration per 5 for 25 seconds.
When you build your SS up, you will be doing great damage. Crazy mid game, you can pretty much own any one or two people you face. I know others get into details, but if you have played Singed, try this one a time or two for a change. If your good at him, you can pretty much do any decent build and rock him out, but this one does some serious poison damage. At lvl 16, you can just run from base all the way up a lane without stopping but for just a second on tank mobs. I usually just toss the tank for the kill. By the end, you have so much gold that you purchase 3 pots every time you get back to base. Try it and shoot me some suggestions.
This is almost too stupid to post, of course you know that not every game goes perfect, but against magic, throw in Abys Scepter or Force of Nature or Bainshee Veil.
Against damage, a good ole Thornmail is the ticket.