Sion was the first champ I purchased and I've never looked back. He is versatile providing a strong physical presence along with a stun and some serious spell damage with death's caress.

This build is designed to allow Sion to have a strong AP presence capable of weathering a beating before being blown up to do some serious damage, while being able to attack and push towers with some serious physical power thanks to his mana, this build scales with mana, simple as that.

These runes are designed to accommodate for Sion's low mana early game when it is the greatest issue and the other runes provide the important cooldown reduction for more spammable death's caress. You may notice they are flat for mana bonus, Sion is fine late game with his items for mana, but early game he is starved for mana. Feel free to change them around and experiment, let me know how it goes!

Pretty straight forward, the masteries help provide mana as well as improving the summoner spell ghost which I usually like with sion, between ghost and his ult, he can get where he needs to be or out of trouble quite handily. The other masteries simply provide good utility and make your deaths caress more dangerous.

Follow the suggested items and you cant go wrong. You will have a decent amount damage output from deaths caress early game to allow for ganking and once you get meki pendant you should be alright for mana if you use it sparingly only against enemy champs or occasionally to farm if the enemy is nowhere to be seen

Your AP and health later on will become a force to be reckoned with as your powerful deaths caress allows easy farming, which in turn adds health thanks to enrage. The farming is very important to gain levels fast and to gain health. For any build the faster the better, but in this case I tend to do alot of ganking early game, which is great for getting items early but I lose out on some experience and health from enrage.

The emphasis early game is to have your powerful deaths caress sweep minions to improve survivability for the late game, while you buy items to focus on AP to provide an incredibly powerful shield, but also an amazing weapon.

The first skill to grab is your stun, simply because this will allow you to get a kill early game if you lane with the right champ and are smart about it. I usually sit in the bushes until an injured or squishy champ comes close enough that i can get them in range of stun before they get away. Even tougher champs and tanks can be killed at this point if you combine deaths caress, stun, ignite and your ally. This is my usual start, but the key to it is to hide in bushes so you can activate your shield which has a 4 sec delay before it can be blown, then charge from bush at an enemy stun them with cryptic gaze then ignite and get a couple hits in. Hopefully this combined with your ally's damage brings them down. It Should.

After this get deaths caress at every chance you get and enrage when you cant get deaths caress. Deaths caress allows for alot of damage output which even tanks will feel in the early game. Deaths caress makes you hard to bring down protecting you from 2 person ganks from most champs, while lowering minion health to a one or two hit kill for gold and hp. But your priority is not just to harass the enemy in your lane, but to kill them fast.

Grab your ult whenever possible, it allows you to crush crowds of minions with deaths caress bringing them down to 2-hit kills. Yes, use the ult on minions, its cooldown is quite low and its nothing special in this build, use for minions and towers and basically activate everytime you get the chance even to just get somewhere faster or run away.

These vary on everyone's playing style and preference, but my suggestion is ignite and ghost.

Ignite - You are going to be in the fight, but you don't have amazing damage output after death's caress goes off and, so finish with ignite, they can run all they want, bet there is no escaping ignite once they are hit.

Ghost - Get where you want faster, very important for chasing down your kills to finish them, because if they are smart they WILL run after they get out of the stun.

Teleport - This summoner spell is great for two uses, allowing a trip back for mana and health at the start of the game without missing much and for getting to the minions in the late game with time to kill them before the enemy can set up a gank. This is how you gain survivability; enrage increase max health for each minion kill and deaths caress kills minions by the dozen.

Other spells:
Flash - for the utility in getting in and out of fights, as well as passing through walls to surprise your enemy, but since you are initiating and don't intend on being killable, not all that useful.

Heal - Heal? Minimal use, becomes quite useless late game and early game sion is quite a strong champ, with proper use of bushes and occasional trips back to base you shouldn't need it.

Exhaust - In combination with your stun it can make champs have trouble getting away, but ignite can finish them even if they do get away. It's usefulness is debatable and the decrease to attack damage doesn't really matter if they are just in most cases going to run. Leave this to your lane mate or a DPS. Your lane mate should be a DPS

The rest- I would not recommend the other spells and don't feel like analyzing each one as to why, but experiment if you like and let me know how it works out. I'd be glad to hear!