Not Updated For Current Season
Welcome to my first guide (somehow I haven't created one after so many games). Shaco is one of my mains and the only real way to play him is jungle. Shaco is fairly item dependent but is a great escape artist/team-fighter if used correctly, and being able to do this effectively is a game changer.
Pure attack speed will help you get through the jungle quickly early. I hit level 4 and done with my jungle around the 4 min mark, super fast. This allows you to gank their jungler (most junglers) at their red buff and come out with first blood. More on that later. Another reason, when you get wriggles, you go super quick and won't have to worry about buying attack speed items right off the bat.
Start with the basic jungling gear with cloth armor and 5 health pots. If you know how to proc the fear right, you should end up with 60% hp and 1 health pot after blue buff. After your first gank, you can get madreds and boots if you get FB, if something goes wrong, get the madreds 1st then try to get boots. If you don't have enough for the lifesteal, grab a health pot or two to help you junlge until you must back and then pick up the wriggles.
After getting wriggles, I see a lot of Shaco players get upgraded boots, but if you are a good jungler, you have red buff most of the time which causes slow and you get kills allowing you to get a quick BF sword to do that mega damage for fairly early in the game then upgraded boots. If you are struggling with ganking and finding yourself under leveled, get the upgraded boots instead of the quick BF sword, help you get through jungle quicker to catch back up.
IE is next on the list which allows you to do a lot of damage on your Q and just hit hard in general followed by phantom dancer which gives you fast attack/move speed as well as increased crit chance. Follow that up with more damage in bloodthirster if time allows to help you stay in fights and finish off foes and finish it up with some confidence in case you are in a tough spot with GA. You should be a backdoor pro at this point and the game should shortly end.
*NOTE* Tanks becoming an issue? You can pick up a Last Whisper to grant you some armor pen and really go to town! You can rid yourself of GA or Blood Thirster for this item...all up to you and how the game is going.
Smite is a DUH on junglers and ignite is good to put damage on while ganking early (damage helps a lot early).
Exhaust can be trumped by flash early game and doesn't slow enough for ghost at times rendering it ineffective laning phase. Ghost is not useful enough late game and again, doesn't help you chase when they have flash and ghost themselves (as most squishy AD chars have).
Creeping / Jungling/FirstBlood
So, how do you jungle Shaco? Fastest (and safest) way is this...as the game pops up, quickly buy the goods and head to the 2 small golems and put 2 boxes just outside proc range. Then put 3 boxes out of lizard range. Right after that the wraiths should have just spawned, go smite the big blue one (don't stay around though because those small ones will hit you). Then go to small golems and then use your boxes to do quick damage. Hit HP pot right after you take damage.
Here is where it takes practice, you can put one box behind golems while you are attacking them. If place it so that the box goes off right before the one you are about to kill dies, the aggro will stay on the bigger golem (if put behind the high hp golem). Then you take no damage and hit the golem with extra damage due to the passive!
Then off to red buff asap because the boxes die after a while. Hit your HP pot right after your first finishes (should be about the same time as you start red buff) *Tip* At lizard, use your shiv to bring out the lizard to the boxes, this allows you to take a little less damage from the lizard elder himself as the small ones are ranged. Right after your boxes die, do the same thing you did with the golems and put one behind the elder and go to town.
After finishing the small lizards, this is where you have to make a choice.
A) If your mid has harassed (but not pushed) the opposing mid, you can go gank mid. Red buff will slow and do some continuous damage and if you can get your mid to jump on board, should be easy killing with your decieve, ignite and red buff. FB (or assist =/)!
*NOTE*: You do not have blue buff, ganking Karthus at this point may not be a good idea as his AOE can still hit you after the gank which may result in loss of life (or lives). If you can't get the kill and they are kiting, just run away and back.
If this occurs, then most likely your mid will be low...tell them to back and you farm up their lane and level to 4 before even getting to blue buff. Once they return (or mid is pushed to tower), go ahead back to your jungle and put a box behind small wraiths, finish those and go on your way.
B) Mid is not open to gank (AOE champ such as Karthus or your mid is an idiot and auto attacking like a boss), go ahead and put a box behind the small wraiths, wait about 2 or 3 seconds and then attack as your box will fear them right after the first attack giving you an extra .3 seconds of not being hit...small things give you big hp advantage. Then wolves, (make sure you hit your pots!) using the same behind the biggest wolf strategy and then off to blue buff where you will use smite to finish (or nearly finish) the bugger.
You now have blue buff at around the 4 min mark and taking in that 4th or 5th hp pot (depending how well you did with your jungle). Assess the situation in the nearest lane and mid and determine if you can gank. Use your best judgement and let the people in the lane initiate, but shortly after, q into the battle and try to strike them in the back...does more damage! If not, you have red, slow, win, FB (hopefully). If you have some good DPS characters in your lane, push the lane as 3 and take 1st early tower and back out at the first sign of danger. Use q effectively!
Say the lanes are not available for a gank...they have an opposing Warwick or Udyr. These two are popular junglers but slower than Shaco for speed. Go to their red buff (on the way place a box at the bush that goes 3 directions, this is a fall back point) and chill in those bushes playing boxes away from the buff but in the bush. Then when they come down to do red, let them get hit a bit and then shiv and do work. With that box in the bush near lane, you will be able to see if anyone is coming to assist the poor fool. If you are scared at any point, run away and q over baron or dragon (or if you think they are trapping you there, q over the wall near the lane and hide in the small golems bush).
Dragon: Shaco can solo dragon with wriggles and being level 6. If the lanes are pushed in your favor, you could ask for help or do it yourself and R (having your clone hit it first so you don't take damage right away). Use boxes for extra damage and save your smite to kill it.
Shaco is a great pusher. If you have a team that can defend a tower 4v5, they should have you go to a sidelane, farm/push it and cause good defense to create a good offensive push. Once you see one leave, back out and find your team and hopefully create a 5v4 offensive counter push in the defended lane...EPIC WIN! Sometimes, they can't get to the lane fast enough and you take tower (ult if necessary) which causes some alarm and confusion for the opposing team.
Team fights. At many points, you will have to be present for teamfights. Shaco is not a good initaitor and gets focused in teamfights. After some ults have been blown (such as galio/amumu/ww) q in and after your first hit, ult as well as put a box next to you giving yourself some protection mid fight and give your team a chance to focus the DPS.
Jungle Shaco early and gank when possible. Even if you don't get the kill, you have put a lot of damage on them and allows your lane to b (and forces them to b as well) giving you a free lane to push/farm/level in.
Don't be afraid to backdoor weakened towers when you get close to late game and have the items. Use your clone to take tower damage and be ready to run away (be creative with your q to get away...sometimes q-ing to the same spot you just were (in bush) are sometimes the most effective because they are 'chasing' you).
Good luck, have fun, should take a little while to get the hang of but is epic win!