Not Updated For Current Season
This build is all about attack speed because Sion already has attack damage becasue of his skill enrage that gives him a huge boost in damage.
The items I listed up there is the order to buy it in not buy then sell for the next item .All the items up there will eventualy be Malady, Mercury treads, 2x phantom dancers, Bloodtristers and Black cleaver.
The reason why I picked mercury treads for boots is because Sion is a lifesteal tank to if he is disabled he wont be able to attack and therefore steal life from hte enemies so mercury treads will shorten the duration of the disable.
In most of my games I pick malady for my first item and people would say "Did sion seriously just make a malady" and I would say yes because malady is a cheap item for life steal, whenever your ult is on cd. It will also give you a nice boost in attack speed which helps in dealing damage.
I buy phantom dancers because the give a huge boost in run speed, attack speed, and evasion. The run speed can help in chasing people and getting away. the attack speed helps with dealing massive Dps. Evasion will give you a little more survivability.
Why buy Bloodthrister and black cleaver
If your games goes on for a long time and you happen to notice you dont do enough damage to the enemy to kill them in a few hits you will want to buy a little more damage. the bloodthrister helps in giving you pure damage and more lifesteal while the black cleaver will take down the enemies tanks in a matter of seconds.
At late game you should sell your malady and buy a frozen mallet for mmore hp and damage and the slowing power will help with killing the enemies
when picking your skills you will want to see if your enemy has a lot fo cc or not a lot of cc. If they have massive amounts of cc I recommend picking cryptic gaze before enrage. But if they dont have a lot of cc enrage is the way to go because you get your early damage which will out damage anyone even Master yis wuju style and give you an easier time last hitting creeps.
In early game you will want to be carefull if the enemy has a lot of cc because at the start of the game Sion is not very strong in armor or hp. So all you will have to do in stand in the bushes and run out whenever you can last hit a creep.
Mid-game around 20min
At mid-game you will most likely have your boots, malady and 2 zeals and aproximately 200 damage which will give you enough attack speed to kill almost anyone with your ult casted and chase most champions with ease. So at this point of the game you should try getting the golem buff and lizard buff and start ganking and pushing other lanes. The lizard buff gives a slowing effect. The golem buff gives mana regen, you need this buff because sion has a low mana pool so he will run out of mana quickly but with the golem he will be able to last a longer time without running out.
At late game you should be able to tank turrets, kill enemy heros and push lanes easily so all you have to do is follow you team and push lanes and win the game.
If your in an arranged team You should ask your support or even a tank to make a Starks Fervor becasue it gives a huge amount of attack speed and lifesteal which will help your team and yourself greatly.