Hey there. This is my first ever build and it explains how I like to play Shaco 3v3. First of all this should only be taken as a guide to help you master shaco more easily. Please take into a count this build suites my play style and may not suit yours.

Shaco is a champion that takes some time to master but with the right timing he can be deadly when it comes to ganking champions.

I play Shaco quite extensively in 3v3. Shaco is also one of the fastest junglers in the game. Being such a fast jungler Shaco can gank and deceive enemies very early in the game as he is going to be level 2 or even 3 while the other enemies are still going to be level 1.

Pros:
- Very fast jungler, with smite he can take down his whole jungle in less than 2 minutes at level 1.
- Can counter-junlge extremely well
- Can gank as early as level 2

Cons:
- Very squishy in lanes
- Hard champ to master

Everything I'm going to show you here will apply to twisted treeline if you plant your jack in the boxes effectively. To be a successful jungler you need to remember the spawn times of all buffs on the map should they be killed. I would put all the times in this guide but they are constantly changing so it would be unreliable.

As soon as you buy your cloth armour and 5x health potions head straight to golem near lizard buff. Wait until the clock hits around about 0:25 seconds before you plant two JackITB's as they might disappear by the time you go to kill golem. Head to where lizard spawns and plant 3 JackITB's just outside of his AOE. If no one has set off your JackITB's by the time the wraiths spawn go and smite the big one (it'll die instantly) and head straight to golem to kill them before your JackITB's disappear. After killing them go to lizard and kill it, which shouldn't be a problem since you have 5 health pots. A helpful tip: always start to kill neutrals while your JackITB is on cooldown because while your attacking it and your JackITB comes back up you can put it behind it and it'll get feared and turn around to kill you box before you, granting you 20% more damage as you are killing it from behind.

After this you can either kill the other wraiths and go for the other golem or look for an early gank.

(Passive) Backstab: Shaco deals 20% bonus damage when striking a unit from behind with his autoattacks or abilities. This passive takes time to master but once learnt it can mean the difference between a kill and not. For example, you can deceive in and go for a backstab which gives you a critical and 20 percent more damage.

(Active): Shaco instantly stealths for 3.5 seconds, blinking to a target nearby location and removing any slow effect. If he uses an autoattack while stealthed, the attack is guaranteed to deal increased damage.
Cooldown: 11 seconds after stealth fades
Range: 500
Levelling Up - Cost: 90 / 80 / 70 / 60 / 50 mana
Increased Damage: 40 / 60 / 80 / 100 / 120%

(Active): Shaco creates a Jack in the Box at the target location with 150 health. It will stealth after 2 seconds and trigger when an enemy comes near, fearing nearby enemies for a few seconds and attacking them. It deals magic damage, and lasts 90 seconds stealthed or 5 seconds while firing. Casting Jack In The Box breaks stealth.
Cooldown: 16 seconds
Range: 400
Trigger Range: 325
Sight Range: 700 (estimate)
Jack in the Box attack speed: 1.359
Levelling Up - Cost: 50 / 55 / 60 / 65 / 70 mana
Fear Duration: 0.5 / 0.75 / 1 / 1.25 / 1.5 seconds
Magic Damage: 35 / 55 / 75 / 95 / 115 (+0.25 per ability power)

(Passive): Shaco's attacks debilitate his targets, reducing their movement speed for 2 seconds. It also causes the minions hit to miss their attacks.
(Active): Shaco throws a dagger to target enemy dealing magic damage and applying his slowing poison to them for 3 seconds. The passive is deactivated during the cooldown.
Cooldown: 8 seconds
Range: 625
Levelling Up - Slow: 20 / 22.5 / 25 / 27.5 / 30 %
Cost: 50 / 55 / 60 / 65 / 70 mana
Magic Damage: 40 / 80 / 120 / 160 / 200 (+1.0 per ability power) (+0.5 per attack damage)

(Active): Shaco creates an illusion of himself nearby which deals 25% less damage and receives 50% extra damage. This illusion deals half damage to towers and inhibitors. On death the illusion explodes dealing damage to nearby enemies. Lasts up to 18 seconds. Using this removes any slow effect.
Cost: 100 mana
AoE radius: 250
Leash radius: 1125
Levelling Up - Cooldown: 100 / 90 / 80 seconds
Magic Damage: 300 / 450 / 600 (+1.0 per ability power)

For my runes I have:
9 Armour Penetration Marks
4 Crit Chance Seals
5 MP5 Seals
6 Crit Damage Glyphs
3 Attack Speed Glyphs
2 Crit Damage Quintessences
1 Armour Penetration Quintessence

This setup allows me to jungle really fast early game and not run out of mana too easily.

For my masteries I take a 21/0/9 build. Nothing really out of the ordinary for Shaco.

My item build is aims mainly at giving me the highest amount of damage output in a short amount of time. It revolves mostly on Attack Damage and Attack Speed. But my Critical Strike Damage is also really high. I open up with cloth armour and 5x health potts for jungling. The first time I come back to base I buy beserkers greaves but boots of speed first if I don't have enough gold. After this I try to build my Bloodthirster as soon as possibly. This item is key to early game domination. After this point I start building my Phantom Dancer buy buying a zeal then a Dagger. After this point I atart building my legendary items that will give me alot of damage output. Starting off with Nashor's Tooth, Gunblade and then an Infinity Edge.

I hope my build was helpful. It wasn't too in depth and I'm sorry for that, but I hope it was helpful none the less.