The Pros: In early game with Sions Q Cryptic Gaze you can stun and use your Critical chance to do some early damage. After you get a phantom and Infinity's edge you start to do some real damage late game. Then by Late game once the build is almost complete after Atma's and all you are waiting on is getting that final blood thirster Is when you start to Wreck the other team.
The Cons: The bad part about this critical chance sion is that you don't have a lot of defense against anything so if you don't get life steal or use your ultimate when you fight your health with drain fast in a team fight. So make sure you get some life steal.

To start off Sion is one of the best champs in League of legends in my opinion. First if you use him Ability Power he is a nuke after awhile. If you use critical chance or strike with him your do some hardcore damage. He also make a great mana tank. But Critical Chance is my favorite way to play him because personally I love doing damage fast. So playing critical chance is the way to go, but the only bad thing is that you will lose health a lot faster than normal without Life steal. But he does amazing early and late if you play it right and your not to risky. Once you get a lot of damage he starts to do work with his stun and enrage giving him even more health and more damage. So Sion with critical chance can be risky but well worth it.

The only thing I say is that you can follow my build correctly or you can get life steal up towards the beginning. Because without life steal sion can not do very well without it he dies to fast. Also Make sure you get Phantom dancer first big item you get he needs attack speed before you get the damage because without it he cant get enough attacks out to do much damage so make sure you get a phantom dancer before you get anything else because without that getting your other items will take along time.

The reasoning behind my skill sequence like that is that i try to max out Cryptic Gaze bore anything because that is the skill that does the most damage in this build without it the build would be way less effective. His Q does everything for him from stunning to get away to stunning to catch up. After i do this i max out enrage I get enrage next because when its maxed out it gives you an incredible amount of Damage towards your overall damage. Then i get the rest of Death Caress in places because with Critical Strike you can really use that because it is more of an ability power Sion skill more than anything. Then of Course get his ultimate at the 3 levels you can.

For farming, His E enrageis what gets him health. So every time you get last hits you get health points added to your total health, so make sure you get all the last hits you can and your overall health will rise a lot. Also make sure you have life steal on when farming because every hit you use enrage on it takes 6 health, So make sure you have life steal so this doesn't take away health just because your trying to kill minions and then lose your overall health when your getting ganked or in a team fight. So life steal will solve that little problem all together

Well this build with Sion is not a tanky build, so you don't want to be the first one into battle until late game. Many ways you can help your team consists of, when they are getting chased you can stun the enemy chasing them. Then after the stun you can start attacking and do damage then your wounded teammate can come back and help finish them off. Also He is an amazing chaser because if he can get close enough he can use his stun and get them stunned then everyone chasing with you or if you are just by yourself. Then once the team catches them they are in trouble. It is also great if your going into a team fight. He can stun the tank and then you can wreck whoever else and then the tank becomes un-stunned and cant help till after he is un-stunned. Also you could stun the carry of the team as in:

Only Stun Twitch if he has been fed, Only because he is crazy good when fed.
Also you need to Stun Tryndamere when he uses his ultimate because then he is just cheap and you can just waste his ultimate.

Basically just stunning and wrecking is what you can do to help your team win.

All together this build works out amazingly for me I do really well with this build. So I have taken some what of my time to give you all the tips and tricks i use to play this character. So i hope this build works out really well for you guys. It should I mean Sion is an amazing champion and in my opinion one of the best in the game. So thank you for reading this hope this helps you if you have any questions or any feedback just comment.

-Phever