Not Updated For Current Season
I've been playing Sion for a quite long time now. I've always loved him, because of his massive amount of health. If you build him right, hes almost unkillable late game. With an amount of approximately 5K health late game, you can really be a huge help for your team. Get in the teamfights and absorb all the damage possible, thats your job as a tank.
A huge help to get the extra kill or help yourself or your teammates to escape. Can be really effective. Now you're probably thinking; "Sion already have a stun, what does he need Exhaust for?" - If your Q ability is on cooldown, you can activate Exhaust, slow them for 3 seconds and pop your stun. Which means that no one is getting away!
Perfect for fleeing, ganking or if you wanna get around the map very quickly. No words to describe it - Sion needs Ghost!
21 in defense because we are building Sion as a tank. 9 in utility because we need the extra mana and health, aswell as improved Ghost.
Because we build Sion as a tank, we need health. I chose to go health in both Marks, Seals and Quintessences. Why? Simple enough;
Marks and Seals has the highest amount of health. Quintessences gives a huge amount of health aswell, and thats what we need.
- I chose to go Ability Power in Glyphs because we need some Ability Power aswell, since we don't wanna be harmless.
Passive: This passive makes sion more of a tank than he already is. He is able to take more damage than normally, which can be great for staying in the lane longer.
Q: This ability is awesome. A stun which not only stun your opponent, but also deals a good amount of damage. This is a perfect ability for getting First Blood or chasing down enemys, or even escaping!
W: With this ability you're not only able to absorb damage, you're also able to take out whole waves of creeps, which is absolutely brilliant for farming and pushing.
E: Increases your damage output and gives you health everytime you kill a target. The combination of this and your Deaths Caress makes it awesome to farm creeps. Not only are you able to kill entire waves of creeps, but it also gives you health!
Can be used to take down waves of creeps if your health is low and you don't wanna Recall. For example; between fights or before fights.
Playing and Items
Start off by buying Doran's Ring and a health potion. Try to lane together with a nuke or CC champion, that gives you potential to make the First Blood. Go into the bushes, pop your stun right before the enemy walks into the bush and throw your Exhaust as the enemy aswell. From there you should have the First Blood, if not - try to switch target if the other enemy overextends, if not - then back off - you don't wanna die.
When you hit level 4, you should have your shield up. Be sure that you use your shield to push the enemys and kill the waves of creeps. Do not use Cryptic Gaze on other than enemys if you think you can pick up the kill. Cryptic Gaze costs ALOT of mana, and Sion has alot of mana problems!
If possible, you might wanna go to that lane where the Golem is, and kill it as soon as possible. Then you dont have to worry about your mana.
When you hit level 6, recall and start bulding your Haunting Guise and you're boots. Now go ahead and kill the Golem. From there, you can start ganking! Take a look at the map, look out for any enemy with low health or help your teammates on another lane (get a kill or 2, and go push that tower). If your own lane needs help, communicate with your team and arrange a gank there.
When your Haunting Guise and boots are done, your next item will be Warmog's Armor. Warmog's Armor is a great items for tank Sion, it gives you health per kill and regeneration. And now, remember what we talked about? When Enrage is activated, it gives you health per kill. So now we have both Enrage AND Warmog's Armor that gives health EVERYTIME you kill something! And remember: Sion is great for killing waves of creeps, which makes it even more epic!
Everything else tactic-wise you should already know. I've added Frozen Mallet if the game is still going after you finished your 6th item, you can exchange your Doran's Ring with a Frozen Mallet.
As a tank your main goal is to get in the team fights, absorb as much as damage as possible, stun and Exhaust any enemy possible, deal as much as damage as possible - and help your team to victory. That is your job as tank Sion!
Hopefully this build will help you out, if not, feel free to post any suggestions in the comments!
-*I'm still editing this, so I'm sorry for any grammar mistakes or whatever. English isn't my first language, so bare with me*-