What did I want when I thought of Sion...

Fast, fast movement, fast attack, good amount of crit.

What I found I needed.

To not get hacked down by the opposition overly specialized on critical strike.

Here is what I came up with, short and sweet, because I'm not much of a talker.

Pretty self explanatory.

A. Greater Mark of Desolation: So you can beat up the non squishes.
B. Greater Seal of Attack Speed: So you can kill the squishes before they spike you.
C. Greater Glyph of Vitality: Stay alive long enough for A and B
D. Greater Quint of Alacrity: See B
E. Greater Quint of Desolation: See A

Really better to change it up depending on your play style. I am vary aggressive.

Standard AD build with mana and speed secondary.

As far as items go I wanted to get a "good bang for the buck". Wile I was trying out different items and such I found it rather hard to get some of the more expensive items. Either because the game was over before I could get to them, or that getting them first really put me at a disadvantage the whole way. So here we are. Just going to post the end item with the exception of Vampiric Scepter which I grab so to better offset his Enrage skill.

1. Doran's Blade for Classic
Prospector's Blade for Dominion
2. Berserker's Greaves
3. Vampiric Scepter
4. Phantom Dancer
5. For caster heavy groups either Bloodthirster (Classic) Sanguine Blade (Dominion)
If you have a melee heavy group go ahead and move Thornmail up to this spot and slide one of the other 2 behind it..
6. Atma's Impaler
7. Thornmail if you still don't have it.

I start off with Cryptic Gaze for the general harassment and if you couple it with Exhaust some early kills. Now since this is a AD build you don't really want to put more points in Cryptic Gaze until the higher levels; all you want here is the stun.

Enrage is really what you want to build points in first. You need to start building up health on minions. It might seem like you don't get a lot per kill but it adds up quickly. Remember you need the killing blow for it to count.

Next I start adding points to Death's Caress you really only need the first level at the start of the match but you could pop it up to 2 if you find you need that little extra health. Then finish off Cryptic Gaze and of course put points in Cannibalism as it comes available.

Exhaust and Ghost when you need them to stay in range and to get where you need to get to fast. You could switch out Surge or Flash depending on your play style but the first 2 get the bonuses from the Masterie in the build.

This build is more for a vary aggressive play style. I tend to run in and die. I'm trying to take as many with me as I can. I have though killed turrets wile getting beat on by one or two of the opposing team on occasion (wile the turret is targeting a minion).

Thanks for reading, hope it helps you on getting Sion to like you :)