This build utilizes Sions ult (Canabalism) and his E (Enrage) alot more then a AP Sion. When you are AP Sion you might rely on your stun and red ball of death. But I have found that AP Sion still owns as well. Its what I love about the guy, he can be anything.

The runes you want is pretty much up to you, but I would pump the attack speed runes and maybe some armor runes just to make him harder to kill. But almost a few crit runes dont go astray.

The masteries I have obviously pumped the attack due to the fact that this build is excellent back doorer and can actually win a losing game I have found.

The Items are very optional. You might not get the money you need to get these things but what you want to work up to is at least 1 bloodthirster, a infinity edge, and the boots of swiftness can be sold at the end it you want to get either a black clever or another phantom dancer to make 3 phantom dancers, and the frozen mallet can be changed for a warmog armor, but I have started going for the frozen mallet just for the slowing effect, even though with all your speed you dont actually need it.

I can't remember the excat sequence, but what you want to do is get your enrage to max level as fast as possible as to start farming it, and have a very hard hit without items. Because your doing a AD build, you can pretty much neglect your W, but still focus on your stun as it is great to catch a enemy off guard. And like with all champs, get your ult whenever it comes up.

The summoners spells kinda are your own preferences, but I like to get to the battle quick with the teleport (which can be very useful for back dooring) and I also like having a escape, which is the flash.

In summary, get alot of attack speed, and attack damage. The attack damage helps your ult alot, and the stun is just used to get a upper hand on your enemy. Though I feel I should warn that with this build, teemo will **** your **** up with his blinding.
"Now I'm dead, serious"