To start off, Shaco is a very good counter jungler especially being ap. Shaco can quickly take blue buff right as it spawns and quickly set up his boxes to counter the enemy jungler. He is a very strong ganker as well as having blue with cdr he can spam his two-shivs landing at least 2 in a gank.

For Runes I decide to take:
Magic Penetration Marks
Flat Armor Seals
Flat Cooldown Reduction Glyphs
Flat Ability Power Quintessence

The reason for Magic Penetration Marks is obvious due to playing ap.
The reason for Flat Armor Seals will give you more survivability in the jungle as well as helping you survive when ganking.
The Reason for Flat Cooldown Reduction Glyphs is so you can spam Two-Shiv as well as having your decieve come back up for a life saver and to place more Jack-in-the-boxes
The Reason for Flat Ability Power Quintessence is so that you can take blue buff without being there and it makes your counter jungling as well as ganking much better as you'll have much more burst damage.

These runes are ESSENTIAL to having dominating when it comes to counter jungle as you need them to take blue buff without being there and being able to put down boxes and smite the enemy wraiths while being able to run back a bit to let go of aggro and then put boxes in the bush.

The reason for having 10 points in the offensive tree is so that you can take magic penetration as well as taking Burning Embers. Taking Burning Embers on the tree will grant you 10 extra ability power which is great to have especially when counter jungling and ganking. It's nice to set up boxes by a bush and see someone walk by then quickly Ignite them to pick up the extra 10 ability power.

As for the 20 points in the Utility Tree we want to have increased movement speed as well as much cdr we can get. The 30% buff duration is also very nice as Shaco is very reliant on blue buff.

These masteries are ESSENTIAL as you'll need them to jungle and counter jungle effentiently.

As for the items, Deathfire Grasp has to be one of the most important items in this build as it is the second of three nukes you have. Using this plus your Two-Shiv will just slaughter any glass cannons as well as bringing down tanking champions to around half health especially when you have your Sorcerer Shoes and Void Staff. Getting Lich Bane is a luxary item as it isn't a must to get. For your last item you can pick up a Banshee's Veil instead of Lich Bane. For Rabadon's Cap it's a must as you need the huge bonus ap to play ap Shaco. Rylai's is one of your only survivabilty items which is something that you need and it goes very nice with your jank in the boxes as it keeps the enemy there longer enough to die with 4 boxes.

For our skills we want to Max out two-shiv as quickly as possible because it is one of our very few nukes. We then max out Jack-in-the-box so that it would do more damage and is great to use for juking people and escaping tight situations by laying it down in front of you as you run away. As for Decieve it really isn't that important and we max last but we take at level 4 and leave it there. We use this skill to gank and run as well as juke and chase. Our ultimate we level whenever we can as it is our last nuke that we have if the clone explodes on them. It's a great skill to use to trick a person in a 1v1 fight as you run and spam two-shiv or use him as bait into a bush of boxes.

For Summoner spells we take Smite and Ignite. Smite is needed for jungling as well as a great skill to have when counter jungling you'll see later in this guide why smite is essential to counter jungling. We need Ignite for the +10 abiity power and since ap Shaco is very limited to having burst damage the DoT of Ignite does well for us. It's also very nice to use against people with plenty of lif steal or spell vamp or heal as it will give us time to nuke them rather than them healing all the damage.

Pros

Has a lot of burst damage
Very tricky and slippery.
Amazing Ganker
Amazing Counter Jungler
Excellent Baiter
Can use boxes as wards
Very deceptive
Plenty of mobility
He's crazy just like you!

Cons

Relies on mana
Very Mana dependant
Relies on the cooldown of his skills
Needs Blue buff whenever possible
Takes a lot of skill and estimation of the enemy knowing who to nuke and when to nuke
Farming is very difficult since you can only farm with two-shiv and jack-in-the-box

Jungling - To jungle as Shaco we start off by placing Jack-in-the-boxes from behind the trees through the trees. We want to place at least 5 boxes behind the Blue buff, that should be enough to kill it without being there, however the mini creeps will still be there just place a box down and kill them. You also want to place a box at wolves by the trees before blue buff comes up then another after you kill blue buff. Throw Two-Shiv at the big wolf and stay towards your boxes make sure to kill the big wolf first. You then run over to wraiths and place a box a away from the wraiths just to the point they won't proc. Run over to mini golems and place one there by the trees just enough so they won't proc. Keep running back and forth placing boxes until you have 2 boxes by wraiths and 2 boxes by mini golems. Smite should be up so you smite the big wraith and let the boxes kill the mini ones. Run back to mini golems and place another box (you should have 3) Two-Shiv a golem and let the boxes kill the golems while you auto attack them. You should be level 3. You can either go back or run into a lane set up some boxes by river and just annoy the enemy with two-shivs or you can farm up to level 4 and take some minions from lanes if they need cover.

Counter Jungling - If they have you should do what you do with blue buff by placing at least 5 boxes behing the blue buff then by 1:30 you want to get ready to run over to enemy wraiths and smite the big wraith. You want to be there by 1:38 so you can lay down a Jack-in-the-box in the bush by wraiths then get ready to smite the big wraith then run to get aggro off of you then return to the bush and keep laying boxes. When blue buff comes up you should be level 2 because the boxes just kill blue buff and you'll have two-shiv. You should have time to lay at least 3-4 boxes which will be death for the jungler. You ignite them first then two-shiv and let the boxes do the rest while you auto attack. Greatest way to refresh your blue buff normally and first blood.

As Shaco you want to plan escape routes for your team by putting boxes in places that you know your team will pass by. Use your boxes to ward and use your clone as bait for your team so that they can wreck the enemies. Make sure you slow enemies that your team is chasing with two-shiv to make their lives much easier. Nuke an enemy champion preferably their glass cannons and decieve away waiting for your two-shiv cooldown to finish then repeat using your two-shiv. By late game two-shiv should be doing over 1,000 from behind the back of a glass cannon and 550 of a tank. If you use your Deathfire Grasp + 2-Shiv your damage burst damage would do double.

For farming you'll just lay down your jack-in-the-boxes by a wave and spam your two-shiv while auto attacking. You can also use your ultimate and let it explode in the center of the creep wave.

Jungling / Counter Jungling Video Coming Soon.