Hi all and welcome to my first build on MOBAfire. Here I will show you how I play Sion as a walking pack of meat that can chop squishies into pieces for seconds (and still being able to survive long in large team fights). When I first played Sion on a 3v3 I wasn't very impressed. I was buying tank items and failed epicly against their DPS Sion. Later I saw an AP Sion on a 5v5 and decided to give Sion another chance. I didn't like it very much but then I tried the DPS way. I felt like it was made for me and here I am, "rescuing" Sion from being forgotten in my champion collection.

Pros
1.Great Ganker
2.Lots of HP even with DPS build (imagine how much will it be when he's tank)
3.Excellent in team fight (your ultimate heals your allies for a % of the DMG done)
4.Good Pusher/Farmer
5.Chops with Da Choppa'!
6.Nice passive that can help you in 1v1
Cons
1.When they see your strength the enemy team will /maybe/ decide to catch you off-guard and gank you 5vs1. I doubt they will succeed if you're with full items because you can just run to your teammates and you will still have HP to fight (maybe about 1/2 or even sometimes 3/4 but I'm not sure). But in case your teammates are close you can turn your ult on and chop some 2 or even 3 unlucky "guys", then retreat to safety and let your allies finish the job.
2. Hmmm... let's think about more...

Pretty standard Melee DPS runes (like Pantheon):
Marks -9xDesolation
Seals -9xEvasion
Glyphs -9xClarity
Quints -3xDesolation

I take a 23/7/0 Mastery Set.
Some would say "Why so much offense?" Well, it ain't so bad and it helps you chop more. TheStrenght of Spirit Mastery on the Defense Tree helps you early game.

Early Game: Start off with aDagger and aMana Potion and head to a lane. Before the patch (v1.0.0.110) I used to start withDoran's Blade and aMana Potion but now I get the blade rarely. Despite this some players still use it although I don't recommend it for first time being with Sion/this build. Anyways let's continue. On first recall upgradethe Dagger toBerserker's Greaves, and buyZeal if possible. Next you're gonna buy aCloak of Agility. Complete thePhantom Dancer when possible and grab aVampiric Scepter next.
Mid Game: Now you'll be looking to get more kills for aB.F.Sword (later upgraded intoBloodthirster) When you get it go for anInfinity Edge.
Late Game: Now you should grabWarmog's Armor (starting withGiant's Belt if possible). Some would say "Why not buy it earlier (passive)" - well, with the HP it gives you few people will dare to interrupt you while clearing the minions on a friendly tower (if not done it may result in a backdoor). You might choose to pick aFrozen Mallet. It's a good item if you're having trouble with catching fleeing enemies (Red Buff can solve this) or just for the extra AD. Final item isAtma's Impaler. For recipe order I like to start with theChain Vest. If you haven't finished yet and you have all items it's almost sure that you win (90% of my games with full item build are successful). After all it does depend on your team.

Your core should look like this:

Berserker's Greaves

Phantom Dancer

The Bloodthirster

Infinity Edge

Doran's Blade orDoran's Shield - Alternative starting items, although I don't recommend them for newbies and for 1st time playing with Sion/this build.

Mercury's Treads and/orQuicksilver Sash - Against heavy CC (crowd control) teams and/or heavy mage teams.

Ninja Tabi - Against heavy AD teams.

Banshee's Veil - Against heavy mage teams (more like teams that use abilities very often).

Randuin's Omen orFrozen Heart orThornmail - Against teams that have many auto-attackers and high AS (Attack Speed).

Madred's Bloodrazor - Against HP stacking champions (Cho'Gath, Mundo, Vlad)

The Black Cleaver and/orLast Whisper - Against heavily armored champions (Rammus, Malphite)

Frozen Mallet - Buy it in case you have trouble catching your opponents (Red Buff.Period.)

Enrage(E) is your priority here. Next isShield (W) and thenStun (Q). And of course level up the ultimate on levels 6,11,16. The next chapter will explain the(E).

Gameplay: Try to get a Katarina laning with you. It's a devastating combo: you stun the friggin unlucky guy and Katarina goes in with ultimate.

1st Case is this: the easiest way as mentioned: Sion stuns the farther one, exhausts the closer one, goes to chop and in the meantime Katarina Shunpoes to the

stunned one and releases ultimate. Here's a quick-made sketch (paint FTW :P) of how it's done with steps:2nd Case, the harder, is this: Katarina initiates with Shunpo to the farther one and right after it Sion stuns the farther one and exhausts the closer one so they can't run out of ult's range and Katarina releases ultimate. Here's another quick-made sketch:BTW don't worry about the tower ranges on the picture, it's just a quick sketch. :)
In team fights stun the squishiest or the one who does the most damage and chop!
Farming: In early game your priority is last-hit, last-hit and again last-hit withEnrage(E). Turn it on only for the last-hit itself, because early game you don't have life steal. The reason for levelingEnrage(E) instead ofShield (W) is that it gives HP whenever you kill a unit (must be activated first) which affects your late game greatly. Just imagine that you're playing Nasus or Veigar (or any champ with similar must-do skills).

I usually takeExhaust &Ignite as Summoner Spells.
Here are other ones you might want to take instead ofIgnite (Mastery procBurning Embers is not set because you're not AP):

Good ones

Flash - Good for escaping ganks early game and getting over walls/obstacles to finish stragglers/escape. On high ELO most players use it always. Very useful.

Ghost - Multiple purposes (versatile) - escaping ganks, chasing stragglers, saving a turret/teammate etc....

Other possible choices

Cleanse - Against heavy Crowd Control teams (stuns, slows, blinds etc.)

Teleport - Pick it in case you have a jungler in the team and you're going solo (after all you need to farm much and maybe you'll save your turret with this)

Not useful/totally useless

Clairvoyance and/orRally - Let a support with the procsMystical Vision orImproved Rally take it/them (like Sona, Nidalee, Sivir, Kayle...)

Fortify - You're not using Da Powa' of Da Tank, you're using Da Powa' of da Choppa'! (Let the tank with the mastery procReinforce take it)

Clarity - You shouldn't be having mana problems (mana starving) with theMana Regen Runes

Smite - You're not a jungler. Period

Revive - Very underrated but I say totally no. You aren't supposed to die so much. Maybe a bit useful for Karthus and Pantheon for their ultimates...

Heal - Very underrated too, can save your *** on other champions but rarely on Sion. Crit + LS + AS + AD + Ulti = FTW.

So this was my first build on MOBAfire. I hope you like it, don't downvote without trying it first or without a good reason and be kind :). And remember - you must last-hit withEnrage(E) so you can use Da Powa' of da Choppa'! efficiently. And just to mention I've had 4800+ HP on a game with Sion (full items but changed some of the offensive ones with HP). The same time me and one Olaf from my team got ambushed and we fought 2vs5 and made an Ace :O And I told the enemy team "Balls to you!" Pity I couldn't Fraps it :(. Anyways, GL&HF while chopping with Sion, The Undead Champion. Cya on the Fields of Justice!

14.02.2011 - Core Items and other situational/optional items will be added soon.
18.02.2011 - Added Core Items + Optional/Situational Items chapters.