Hello summoners,

First of all I'm VAIR ee taws one of the many League of legend players in Europe. Sorry for my bad English but it's not my 1st language. First of all I would like to say check out this awesome build as I find it and rate it in all honesty. Cheers guys.
My first Sion guide and absoluty my last. All those who are fan(s) of the AP Sion won't or maybe find themselves pleased with this one.
As it brings alot of fun and brain into this game.
I will talk and explain some of my tactics and item build I use on my Sion.
This Guide will be in the spotlight of a critical Sion build, Enjoy.

Pros

- Great farming capabilities
- Awesome stun, nuke damage.
- Great damage output using crits.
- Very mobile, fast. Having your Mobility Boots and Trinity Force.
- Strong and tough, not as squichy as most other DPS champions.

Cons

- Squichy early game, mid game.
- Easy team target, trust me they want you dead.
- When stunned or snared you are not able to escape fast when your Cleanse is on cooldown.
- When not fed enough can be hard till late game to get controle back.

Runes are quite formuliar with this critical build.
I usually really like to do massive crit damage early game, early ganks.
So I've chosen to use all my runes as Critical chance.
Which gives you in total 20% crit chance.

Using your masteries with crit gives you ingame without any items: 22% critical strike chance.
This is an amazing early game boost as your chances are very high to crit on level 1.

Masteries are 22 in Offense and only 8 in Utility. Cause I find a good offense a better defense. Especially when you are a fighter and must act tough

Cleanse is my favorite summoner spell. There is a lot of CC (Crowd control) in this game, alot of snares, stunes and exhaust which u may not forget. Cleanse helps you escape in most cases or even chase better.

Ignite Ignite is a very handy skill, especially to get your first kills. During your great criticals your opponent will run back to a nearby tower. To get the last HP of ignite will do the job for you. Also late game healers like mundo can be easily stopped by using ignite on them.

The core items are very similiar. A known selection of items that are used on many champions.

Trinity Force
Mobility Boots
Infinity Edge
Phantom Dancer
Bloodthirster
Last Whisper

These are the items you will have at the end of a very long game. These are all very expensive to buy but as this Sion youll be able to kill anyone in your path. And Sion is a excellent farmer.
I usually won't make it as far as Phantom Dancer during ranked games, most of the time the game is then won or lost.

Sion's skills

Let's take a quick look which skills Sion is using.

Q Cryptic Gaze
Excellent stun for 2 sec. Also does magic damage. A nice damage output early levels. And a great gank ability.

W Death's Caress
Great defensive/offensive shield by Sion. Does magic damage when explodes but it mainly protects you from incoming damage. Late game this will be your small shield when going into battle! Very usefull skill. To harrass but also to escape a nasty death. When you're health is down to 0 you can try to run away and pop up your W skill and hope it will last enough to survive.

E Enrage
This is why Sion is such a great AD/Dps'r in my opinion. This skill gives you +AD on activation. Each hit cost health depends on which level the skill is but early game this is what feeds Sion. In combo with your critical chance you kill squichy's very fast. Excellent skill, I personally always keep this on unless I really can't miss the HP it's taken every hit. It's great to farm and kill.

R Cannibalism
Sion's ultimate. This is a skill where the fun part comes. Eventually late game you'll be fighting till the death and when you activate your ultimate you'll get on level 16 +100% lifesteal and so on. Which makes you nearly immortal in 1v1's. You'll only be able to get killed when a few peole stun/focus you. Great skill, great to survive and to gain some extra attack speed on the way.

Early game

Let's talk about the early game. You setup your runes, masteries correct. As soon the game is loaded you'll start of with Brawler's Gloves and run to your lane (In my case it's usually bottem lane). Start to last hit minions if you are able to. If you're playing against champions with range like Ashe or Sivir try to be carefull till level 4. When you reached level 4 you start to harrass with your partner. There is a combo I use for that which is commently used by Sion players. First pop up your W skill Death's Caress stun your target (most squichy'd with Q Cryptic Gaze. I always keep E skill on which is Enrage. Gives you extra damage and on early game the firstblood or first kills are always the once that makes your game easier. So take advantage of your high dmg output. Try to harrass your opponent as much as you can and try to push them abit away from the minions so they won't get any income exp or money.

Mid game

You reached level 6 and the game has really begun. Ally's dropping on other lanes or maybe even owning there own lanes (Which is always best ^^) try to plan a gank on someone on your lane. Try to get your jungler or mid laner to yours and set up a gank. Stun Q, activate your ultimate and smash that B*atch into the ground. This is the way to get trough mid game and feed yourself enough to get ready for late game where the nasty teamfights start. Also when your lane is totally secured and there is nothing much to do then just farm minions and harrass your opponents. Try to get away from your lane and setup a gank somewhere else. Sion is nearly one of the best gankers during his stun and damage output. So take advantage from that, it helps yourself and your team. A victory is closer by.

Late game

Late game, I most times hold it up till late game. Tanks start to grow, damage is getting better.. Teamfights start. In this case you are important. Very important. You can target the ones you'd like to be killed. Ping your target, stun it and kill it. Do this as a team and never alone. Sion is very strong in a group but not so strong alone. I always wait for the right moments to go in, wait for your tank to do some CC like Amumu's ultimate. Take advantage of the weak and focus them when a teamfight takes place. It's important that you stun the right target most times DPS carry like Ashe or Pantheon. Those are the champions you don't want to last in a fight. It's important that you communicate about which opponent you focus. Also your momevement speed is great. I like to leave the team for a bit move to top or bot lane and push the minions a bit. So when you start a teamfight they forget about there other lanes which u have pushed. Very nasty when they see there towers under attack by a bunch of minions. Helps killing there base faster, Pinning enemies down.

Thanks for reading my guide and hopefully trying it. Cheers.

And ofcourse some promising results, for those who not believe this can work.
I'm around 1400 rating points.