I've been testing Sion for a long time now, and I find that this is his best build. I've tried him AD, I've tried him AP, I've done a hybrid deal with the Undead Champion but I don't find they use him to his fullest potential!

This Sion is a Tank. Pure and simple, he takes a ton of damage and deals out even more. Thanks to his amazing abilities, he is a super effective solo lane, as well as a great at providing assists when paired with someone else.

* I must note that while I've played with this build in 5v5 it is optimized for 3v3 *

-- Please remember that every game is different --

With your teammates head straight to the bottom bush, there you should either stun the slowest Champion, or the one with the lowest health (unless you decide with your team on another target). Once stunned head in for the kill and help your team. As soon as they have been taken care of, or the first minion wave is about to spawn, leave for top.

Soloing top you should dart in and out of bushes stunning and harassing the enemy, try and farm as much as possible while in lane, last shot minions as much as possible. This is a priority for your Enrage ability to gain you life. You should be able to discourage the Champion you are against and push harder to tower. Remember, against some champions you may have to continually harass even if that means you start getting pushed back.

[*] Key moves for early game is to use your shield. Time it so that you can stun, run up attacking the enemy Champion, and explode it for additional damage.

[*] Should you ever die and an enemy anywhere on the field is near dead, Revive yourself and run back into combat. You should use this Summoner ability as often as possible!

While playing keep a track on your level. With all your abilities off cooldown you should be able to aolo dragon with their use at level 9. As soon as you get a chance, take out dragon for the team buff and extra gold. Should you have enough health and mana, take on the Black Buff Wraith.

Once you move from Mid to Late gameplay, you'll have to use your judgement on how to play. With your speed and damage you can fly around the field ganking, killing minions, and taking down towers. At this point I tend to notice that Summoners will focus on me more. This isn't a bad thing however, it means your teammates will be able to clean up after you or take down unwanted structures.

Early game Sion is not as powerful as he will soon be. It's important to have Runes that maximize his abilities and capability of taking out a target.

[*] The Greater Mark of Desolation / Greater Quintessence of Desolation
These allow for Armor Penetration, the extra damage that these provide in game are essential to keeping up your kill count and your to discourage other Summoners from coming close.

[*] The Greater Seal of Fortitude
The more health you have in this game, the better! This rune choice is my preferred favorite, however, you can also take 9x Greater Seal of Resilience if you prefer armor over health.

[*] The Greater Glyph of Alacrity
In theme with this Sion, attack speed is one of the most important qualities to upgrade... so then why is it not in my Marks? I find armor penetration a better flat need then attack speed is. With the item choice, you can upgrade your attack speed.

Instead of focusing on Attack Damage or Ability Power this build focuses on Sion's survivability. With abilities like a Stun, a Shield, and Lifesteal Sion is one hard Champion to bring down. By taking mostly defensive masteries you make that Tank even more difficult to take down. However, if a team beings you down, you now spend less time dead and can get back to the fight faster.

More to Come! Tell me what you think!