So sion is by far my favourite champion to play, he is super OP if you know how to use him
he has some powerspikes that i will exploit soon

So pros and cons :
PROS:
1:he has alot of AoE waveclear with his kit so you should be able to melt down camps pretty fast
2:although his ganking power pre 6 is bad , you can gank if your enemy over extends and pushes so far pre 6
3:has by far one of the best ganking tools that the enemy doesn't expect at all when ganking
4:scales super hard in the lategame and can snowball the fck outta his team and himself

CONS:
1:his passive is sorta useless unless you know what to do with it
2:his ganking pre 6 is so situational so it's not good
3:he cannot pressure the game as well as other junglers can because his ganking without his ulti is outright bad
4:his early game isn't the strongest and gets countered by high mobility champs pretty hard

so whenever you are jungling keep an eye out on your W health , and try to use it before it runs out because it has by far the most damage in your kit
counterjungling with sion is pretty good against weak junglers as amumu
whenever you cannot gank keep on farming , level is key on sion , the sooner you get 6 the sooner you gank

so sion's R is pretty hard to use right? well you can use it close up to destroy people whenever they aren't expecting it , and if you get enough CDR late game ur R is on about 30 secs cooldown so people will not expect your R most of the time

so ulting in teamfights and staying in the frontline is really good , if your team can peel for your carries go in the frontline and use ur Q offensivly , if not , use ur Q whenever someone jumps on your ADC/mage
because of your high damage and your very strong item buildpath , you will be destroying people lategame , but be wary of junglers like rammus or shyvana who can outskale you pretty hard , so if you do not have a good lategame comp , don't do it
last tip : your E's Slow is so strong when you hit a minion into a champ with it , so use ur E+Q in teamfights so nobody can catch you out , also , stealing baron with R+Smite would be a good idea , just watch out for counter walls like trundle's pillar , azir's R , anivia's wall , etc