5v5 Singed should be played as an all-destroying, suicidal carry of the highest degree.

This build stresses the factors that make a player successful at high ELO. Farming, objectives, map control, teamwork. Its about farming as much as possible while still managing to help the team do important things like towers and dragon.

GOALS:

• Farm every possible bit of gold and experience from minions
• Destroy towers and help your team dragon
• Initiate fights and seriously disrupt the enemy team
• Deal huge damage and absorb huge damage

There are a few key points around which this build is centered.

• Scaling Glyphs and Seals
• Gold per 5 items
• Teleport
• Archmage's Savvy (0.6 AP/level), Ardor (+4% AP), Tenacity (-4% damage taken), Good Hands (-10% death timer), Awareness
• Solo Lane

As may become clear, this build is all about getting as much exp and gold as possible and then doing what Singed does best and destroying the enemy team. Gold/10 items and scaling runes maximize Singed's lategame potential. Teleport and solo lane ensure he reaches high level with lots of gold as quickly as possible.

I must stress VERY strongly that everything is a balance. You can't go gold/10 quints, full utility tree and 2 gold/10 items. This build, in my experience, maximizes Singed's potential throughout the game. Early HP and Armor help the team by making Singed an expert diver, which will cause chaos to reign among any but the highest ELO players.

"Carry Potential"
Archmage's Savvy provides 16AP at level 18 (12AP + 34%) at level 18.
Ardor is equivalent to about 16 AP at level 18 (4% of 400). Even affects the 65 AP from Insanity Potion.
Archaic Knowledge - Adds 2.5% more damage if the opponent has 30MR. 9% more damage if the opponent has 150 MR. Just too good to give up.
Tenacity - 4% damage reduction at a full build is basically equal to 160 HP. That is game-changing.
Defensive Mastery/Harden Skin - This is 3.5 damage reduction applied AFTER armor. Singed tanks a LOT of creep damage while farming and harrassing and these two masteries are essentially to playing an unstoppable Singed.
Hardiness/Resistance - This build doesn't contain that much Armor/MR (largely due to the 65 from Singed's ultimate). These two masteries help offset that weakness (they're efficient due to the high HP in this build).


Masteries I did NOT select (the utility tree explained).
Spatial Accuracy & Haste - A real tragedy, since these two spells add a significant amount to Singed's mobility throughout the game.
Awareness - I am so so sad I can't take this. 5% more exp gets you to 18 slightly faster.
Expanded Mind - Only applies to base mana (as of 9/18/2011). Essentially adds 50 mana and 13HP at level 18 (for four points). If this applied to item mana, I'd consider using the utility tree.
Greed - Equal to 180 gold at 30 minutes, or about 9 AP. I'd definitely select this if I could go down the Utility tree further, but Archmage's Savvy is just too valuable.
Meditation - By pulsing poison on-and-off in quick bursts, Singed avoids serious mana problems and should be able to get by in-between teleports. Still, this is a nice mastery for a Singed beginner.
Quickness - Move speed is nice on Singed, but the truth is that there are soft caps on movespeed. Ultimate and Ghost together put you well into that region. Combined with Singed's Amazing slow, this mastery just isn't that necessary.

Early game you should last hit. You should poison waves when you're ready to push the tower hard, but you need to have the river warded to avoid ganks (ghost plus ultimate plus slow helps to escape, but only if you can see the enemy coming).

As the game progresses, you should be farming every lane you can. Don't let minion waves die with no one around. If an ally dies, teleport to their lane before the tower kills minions. Teleport is your farming ally and should net you a level or two above all allies and enemies. If you're pushing hard, kill the top golems in between every fourth minion wave for 60 bonus gold.