My name is Babylonius, im the Jungler for Team Faction, also known as Faction Games (we started out recently) i was Silver in Season 4, and generally am a person of no importance at all, but i'd like to share whatever little bit of information i got

-Pros
Tanky
High scaling abilities
Strong Initiator
Unlimited health scaling
Strong in teamfights
Hard to kill

-Cons
Prone to being kited
Not as strong in 1v1 situations
Needs to get up close and personal

For items, i like to use Frozen Mallet for its on-hit slow which Sion benefits from, as he he's prone to being kited, especially during his passive, Spirit Visage is useful due to his passive as well, Sunfire Cape is near mandatory on tank junglers to increase their clearspeed, Sion is no expection, Skirmishers Saber is great for tanks due to their ability to take more damage from a target that deals a large amount of damage and the Juggernaut enchantment gives a nice amount of tenacity, while granting health as well, Hydra works great as a sole damage item due to its health regen, active and large amount of AD and the lifesteal is a nice benefit as well, the mobility boots can be switched out for Ninja Tabi later on in the game when the laning phase is over

9/21/0 is a basic Mastery setup for tanks, maintaining a high defense throughout the game while storming in with a decent amount of damage

Marks: Attack Damage Marks for increased clear speed, and it provides a small amount of extra damage for ganks, which can come in handy quite a bit

Seals: Armor Seals, these are mandatory and should always be taken

Glyphs: Magic Resist Glyphs, for more overal tankyness, these can be switched in for Health Glyphs if you're going against a team thats more AD

Quints: Health Percent Quints, they will give you an extremely high amount of health in the late-game, as you're health scales infinitely, so will the health granted from these quints

Sion's Infinite Health Stacking

Sion is the only champion in the game who can stack his health infinitely thanks to the passive from his W, this should be taken into account that Sion becomes progressively harder to kill as the game continues to go on, if any lanes have big minion waves headed your way, ask your team if its ok that you clear those instead, as you will make more use of the CS than they will, but in cases where somebody of your team is behind and needs to catch up more than you do, its best to let them take it instead

Sion can activate his W during his other abilities, make use of this to improve your cleartime by activating your W during the charge up of your Q or during your ult to peel more during your initiation and make use of the slow of your E to catch up with fleeing enemies by knocking a minion into them and dont forget that Sion's ult has an extremely low cooldown at rank 3, dont be afraid to run away from enemies with it late-game as its a strong way to make sure your team doesnt get completely aced

So this was the guide, i hope you people who read this can make use of it, ill update it once patch 5.4 goes live since thats when the Juggernaut enchantment for the jungle items gets changed into the Cinderhulk enchantment

i admin a facebook page named "We Are ADC's", feel free to check it out if you're interested
https://www.facebook.com/WeAreADCs1

have a good day