Shaco is a ganking champion.

The reasons to play this champion:
1 - Stealth
2 - Guaranteed crit with stealth
3 - Red buff at level 1
4 - Gank at level 2
5 - Gank all laning phase
6 - Mind games

First I would recommend that this champion only be used in Solo Queue or Duo Queue. Shaco is not very hard to counter, and if he is countered, you have a very small chance of succeeding as Shaco.

In Solo Queue, we all know that our partners generally suck/feed. Well, there are 2 things you can do about this.

1 - Carry hard
2 - Make sure your team wins their lanes

I figure option 2 is far easier than option 1.

Shaco has the ability to apply lane pressure like you've never known. One "failed" Shaco gank that only successfully lands 1 hit and 1 two-shiv can potentially devastate the enemy laner.

This guide is based upon:
1 - pressuring the lanes so that your teammate may come out on top
A - making your free crit hit as hard as possible
2 - making nerfed shaco viable later in the game
A - giving you maximum maneuverability and some tankiness

This Guide will not be what you normally see shaco guides try to accomplish. We are not maxing attack speed. The reasons:
1 - attack speed is for sustained combat, shaco does NOT want sustained combat! He is ultra squishy!
2 - attack speed does not abuse his free crit!

Crit damage, all the way. Shaco shouldn't have trouble jungling without his attack speed runes, the 20.07% crit damage should make up for the lack of 12.6% attack speed, at least somewhat.

This is meant to abuse your free crit.

Impact:
Gank at level 2 right after red + 1 wraith =
Shaco's damage at level 2 = 54.5
Shaco's extra crit damage from level 1 Q = 40% (this is a crit, but not a x2 crit)
Shaco's extra crit from marks = 20.07%

So:
54.5 X (.2007+.4) = 54.5 X 1.6007 = ~87

This is only factoring in marks. The calculations in other chapters will be cumulative of the previous chapters. This applies to goal 1 of shaco.

Crit damage, no alternative.

Other than marks and Quints, these give the most.

Referring back to the previous crit damage total at level 2 from Marks:

54.5 X 1.6007

Now we are going to add 7.02% from the seals.

54.5 X (1.6007 + .0702) = 54.5 X 1.6709 = 91

This factors in marks and seals, other chapters will be cumulative of previous chapters.

A: Shaco needs cooldown reduction. As much as people think this is "Noobish," Shaco's ability to teamfight is very sad. The goal here is to enter the teamfight stealthed, and target the enemy carry/squishy. Pop him with your ridiculous free crit, pop ult, go at him. The quicker you have the ability to stealth again, the greater your chance of survival/killing the carry/killing another target. Q is essential to teamfights, the more of it, the more effective the shaco. Glass cannon crazy attack speed shaco will be instant focus = die. So what we plan for is Blue buff + ionian cooldown boots + cooldown mastery. This leaves 2% cdr required, so 2 X .9 cdr at level 18, we have 39.98% cdr. Perfect, or near it. This gives you a 6.6 second Q. Trimming 4.4 seconds off of the initial 11 second Q. That's A LOT bigger chance of survivability.

B: Shaco is very squishy. Magic resistance is very crucial for him. 100 magic resistance is 50% damage mitigation and is our goal. With the build shaco will have 80 magic resistance, so an extra 7 X 2.7 mag res at level 18 = 18.9. This gives him 98.9 mag res, very near our goal.

Both of these apply to goal 2 of shaco.

More crit damage abuse.

13.38% crit damage added.

Back to our old formula that's still building:

54.5 X 1.6709 + quints

54.5 X (1.6709 + .1338) = 54.5 X 1.8047 = ~98

This applies to goal 1 of shaco.

Offensive:

You want the Offensive, for CDR = 3%
Crit damage = +10%
And overall damage = +4%

How this affects you
1 - refer to glyphs Part A to see CDR impacts.
2 - Crit damage

Referring to our accumulating formula:

54.5 X 2.8047 + masteries = 54.5 X (2.8047 + .1) = 54.5 X 1.9047 = ~104

3 - now apply the 4% increase

~104 X 1.04 = ~108. (my math is done without rounding, just posting rounding, this will give slight mathematical errors as the formula accumulates buffs.)

Also, we will finally add in shaco's passive. I'm not sure if it applies before or after the crit, so i will add it in as if it were crit damage, so as not to inflate the value.

(54.5 X 2.1047) X 1.04 = ~119

Hitting mid with this at mid's level 1 is approx 1/3 health. The mid squishy should drop like a fly with a little help from mid. Ashe initial crit + shaco initial crit + burn damage from red buff should drop mid almost instantly.

Utility:
1 - improved ghost is very nice
2 - perseverance helps your potions/any heals heal you more
3 - experience mastery is just nice
4 - 1 in the Utility mastery is very nice for the 15% bonus buff duration. (it is also viable to sacrifice the 4% damage from offense to put it in this, if you feel buffs are more important.)

This all applies to goal 1 of shaco.

Smite: Shaco is going to jungle, at least to get red. If you are comfortable jungling with shaco without smite, then go for exhaust or ignite.
Applies to goal 1 of shaco

Ghost: This is very very nice to ensure you get your free crit while ganking early because you are slow and your Q stealth only has a 3.5 second window. Later it is nice to help catch/escape.
Applies to goal 1 and 2 of shaco.

Wriggles:
Helps you jungle
Helps you survive in teamfights via lifesteal
Helps wards to ensure your teammates awareness/survival

Applies to goal 1 and 2 of shaco.

Ionian Boots of lucidity:
This is definitely going to be the area of criticism (although I am firmly confident in this choice.)

Boots of mobility won't help you escape, and they are expensive and must be bought early. This is a hindrance.
Boots of swiftness offer very little in a teamfight.
CDR is extremely important on shaco due to his high cd on Q. (Not to mention his ult.)
See chapter: Glyphs, part A.


Infinity edge. This is very important. This item adds + 80 AD, 25% crit chance, and 50% crit damage. It is the quintessential item revolving around Shaco's current prowess.
This will turn your crit damage into 340.47% of your attack damage. X .04 from the offensive mastery. (When deceive is level 5)***

It is acceptable to build BF sword, then Zeal for the movespeed, AS, and survivability/lethality that comes along with it.

Triforce: This item does not need to be completed at this moment. It is acceptable to build zeal alone before moving on in the build. Or zeal + sheen, etc. THIS ITEM IS OKAY TO BE COMPLETED LATER IN THE GAME. It gives you tankiness, movespeed, attack speed, and makes your initial crit out of stealth even MORE powerful with its proc. This item ensures death to the enemy carry.

Banshee's: This item is very important to shaco. He needs some tankiness and banshees is a fantastic item for that purpose. It's passive, MR, and health make the wearer much tankier.

Cloak and dagger: This item can be put into the build at any point in which you feel you need it. Or top it off at the end. Shaco stunned is a sad shaco. Tenacity is extremely valuable.

Wriggles may be subbed out for another lifesteal item if the game allows it. Starks is an excellent choice, so is bloodthirster. (thirster harnesses the crit abuse a bit more than stark's pen.)

I do not expect this build to be completed in game, if it is, you did not do your job correctly.

Reasonably you should end with this build:
Wriggles, Ionian boots of lucidity, Infinity Edge, Zeal, Negatron cloak.
Or
Wriggles, Ionian boots of lucidity, Infinity Edge, Zeal, Sheen (if you have no trouble surviving).
Or
Wriggles, Ionian boots of lucidity, Infinity Edge, Zeal, cloak and dagger (if you find CC is more destructive to you than mag damage.)

His build can be tweaked a few ways. But some items are crucial. The first four in the above 3 builds are those that are crucial.

With this guide you should have:

Around a 6.6 second Q.
A good chunk of health.
A good bit of mag res and armor.
A ridiculous Crit out of your Q (and of course, zeal and IE give you a good chance to crit upon fighting anyway.)

You will be impressed by what this shaco can do.

I assume many shaco players know how to manuever as shaco, but I will offer some tips.

1)
Start at red.
Kill 1 wraith to get level 2.
Gank mid.

2)
Use ghost for your early ganks if available. Before you acquire some movespeed, you want to make sure you get your Q proc.

3)
You don't have to kill the enemy to successfully play as shaco.

4)
After you hit with your free crit, drop a jack in the box in the enemy's path (which should be behind you because you should hit your enemy from behind).

5)
Two-shiv the enemy as they get out of your range, don't miss this free damage.

6)
Use jack in the boxes to start jungle creeps, deceive before the box fears, then crit the minion in the back while it attacks the box. This increases jungle speed.

7)
You can drag at level 6 fairly easy if you,
A: Use ult first.
B: Deceive behind the dragon.
C: Initiate with your clone.
D: Free crit dragon in the back.
E: Smite the dragon from behind.
Dragon is very important to get early, so that you have dragon timer to continue to get dragon later.

8)
If the enemy is countering you with wards, don't be hesitant to buy an oracles! It may be your only chance to salvage shaco's use.

9)
Shaco can b/d well and escape. Have jack in the boxes prepared to cover your exit.



PS:
I hope this guide was informative and offered to you a new perspective on shaco. Perhaps if enough people read this, we may find shaco a more viable champion.

Warning: In Premades, this champion is easily countered via: CV, Wards, Oracles, Pink wards, excessive tower hugging, and early jungle invasion.

Before damage mitigation, this whole build will land 3.4047 X 247 + 165 = 1006 damage in 1 hit.

Q - Deceive
This is a crit, but not a standard X 2 crit. It is a X .4/.6/.8/.1/1.2 Crit. A X2 crit cannot occur to stack with this. However, crit damage runes/masteries will increase deceive's crit damage.

Triforce
I am not sure yet if triforce's proc gets multiplied by the crit, but I will test it very soon.