This particular build isn't really the best for those who are just beginning to play as Shaco and is more for the people who have started unlocking Shaco's potential already strictly because of the level of the items in the build. Read through the build if you like it rank it if you dont then do whatever you want with it because this build is mainly for people that hate it when they cant outrun Teemo and Master Yi and cant get the hard hits that they are looking for. This is NOT a jungling build so dont use it for that this is a lane build and you will not benefit well from jungling with this build and are better off to use someone else's build other than mine.
I have made a few revisions based on the comments and changed the masteries up a bit and I hope this helps the games go better this is my first guide and any comments you have to make this guide better are greatly appreciated.

I have these rune choices mainly because of Shacos first ability and how it auto crits when it is under affect, the runes focus on his ability to jump in hit hard and fast and get the heck out before anyone touches him and if you wanted to substitute some of the crit chance runes for movement speed, damage or Ap then have at it.

The items ive chosen for shaco is to focus on his ability to kill fast before the enemy can take advantage of his squishiness. Personally I think that the Phantom Dancer was made for Shaco to use because of its speed boosts as well as the crit percentage. Youmuu's Ghostblade is good for Shaco as well because of its crit bonus and its active that I love sooooo much, not to mention the armor pen. and 15% cooldown reduction. I switched out the Randuins for a Lich Bane because while giving you 30 magic resist it also gives you ability power, mana and movement speed which still holds within the build area getting this along with the other switched items and everything else really rounds down the rough edges on shaco. Every character in the game should have some form of oracle or sight to let them see the enemy when no one is there to help cover monsters like Baron Nasher and the dragon no matter what game your playing but Wriggle's Lantern gives you one free every 3 min and you get added armor, attack damage and 15% life steal not to mention its passive which can on chance deal 425 magic damage on a minion/monster which really helps when fighting any of the buffing monsters, it is technically a smite, sight ward and Chain vest all in one. Getting an Archangel's staff grants extra ability power plus what you get from the mana boost if you read up on the archangel and 25 mana regen, this gives you a massive amount of ability power late game making shaco AD and AP also with shaco's armor levels he is sturdy too so this makes him hard to kill and a hard hitter. If the other team is terrible and you cant stop getting kills then you can completely forget about the Youmuu's Ghostblade and just get another Phantom Dancer which will up your speed greatly with the loss of Youmuu's active.

Flash is always good to have and ten times better when added to Shacos natural escape because you can just hop over a wall using the natural and then flash over the next and after another few seconds of running you can use your natural again making three escapes in a matter of about 15 seconds then when you throw in Ghost your Shaco becomes pretty much the best escape artist in the game because you can outrun any character especially if you get a second Phantom Dancer.

Pros with this build:
[*] has a natural escape mechanism
[*] fast as heck
[*] crit chance and damage are threw the roof
[*] a ridiculous amount of armor for an assassin as bonus
[*] great amount of health and health regen

Cons with this build:
[*] Magic resist isn't that good
[*] Magic and Armor penetration aren't good
[*] Ability power isn't amazing
[*] Susceptible to CC's

Never be the first to initiate and always start from the sidelines so that you come in unexpected during team fights. Along with your wriggle's lantern set boxes at possible points where the enemy will try and gank you so that you can see them and alert you team before the enemy gets there so that your team will be safe, the boxes will also hurt most enemy champions so make sure to use that to your advantage because they will become wary of them as with teemos shrooms. When entering a team fight look for there squishy powerhouse and flash in with deceive and crit them, set a box, watch fear ensue (due to boxes) and throw a shiv at the powerhouse then either flash out (if deceive isn't ready) to stay safe or if most of the enemy team is dead join the fun and use all that crit power you have to finish the remainder of there team in a matter of seconds.

Farming mid and late game is relatively easy with Shacos massive attack speed but is bad late game so the more you use the boxes to help the better you are and when farming don't use you poison shivs because when they are on cool-down it removes the passive against minions. Try to last hit minions and kill them right before they hit the turrets agro in the sweet spot so that enemies are less inclined to attack you in fear of your turret.

With this build you should be able to dominate the field with your team and dont forget while using the build that this Shaco is extremely DPS and may or may not be good at jungling so dont take too many chances with jungling early game. Hope you benefit from this build and go out and win a **** ton of fights with shaco.