Welcome to my AP shaco build. Its mostly a Magic pen build , makes killing high hp tanks/off tanks alot easier,

Pros :
High damage from boxes if baited correctly
High damage from shiv and ults
Easy escape mechanism
Ap boxes makes it easier to jungle

Cons:
Tend to be focused on in team fights
Expensive build
People tend to know when being baited into boxes late game

I picked these runes because:
Easier early game with high Magic pen to get kills with boxes
High Ap flats for shiv ult and boxes
One lower cooldown quint because 15 sec's is along time for boxes if you dont jungle for blue
And Insights for high Magic pen

I chose 9 - 0 - 21 masteries because :

Nice chunk of AP per level, Lower cooldowns and More magic pen.

And i chose to fill utility tree because it can make it easy to lane without blue with mana regen and lower cooldowns

(I'm also open to your own masteries build , this isnt set in stone)

One point in jack in the box first because quite easy to get first blood with 6-7 boxes in a bush top or bot.
Then you want to start maxing out Shiv and Decieve
I always go shiv first because of the slowing effect helps the boxes get much more damage on the champ with fear then slow
Then decieve to get out of a bad situation or to get that final reach to kill a champ
Hallucinate is a very good ability in my honest opinion, As long as you dont have say a buff on you, You can confuse the opposition bait them into boxes, get away from ganks

Early game pick up a dorans ring and get into your bush either top or bottom lanes, then if you dont get rushed you want to start piling boxes at the back of the bush so the minion waves wont set them off.
If you've got 5-6 boxes in the bush with a good laning partner and the opposite sides champs rush into the bush you should get First blood or assists, But dont try to force it try and bait them into your bush, Your pretty squishy level 1-5 so dont think your invicible
Start piling boxes into there bushes if there dead/back , try to only last hit minions too, Especially if they have a jungler, dont over extend early game

By now laning phase should be over , and team fights happening.
Always try to bait onto your boxes with team fights it gives you a great advantage when they are feared and taking a boat load of damage with your boxes.
If you cant thats fine too, If a champ gets too close shiv them and move back. And try to decieve in and out of the team fights to get a good box placement in the middle of there team during the fight
Boxes can also be Defencsive as well as Offencive, if shiv,decieve,hallucinate doesnt get you away then plant a box as your running gives you a nice clear run while there feared
Always box dragon and Baron, and both teams Buff's if you have the time

Now you should be doing alot of damage with your shiv and boxes.
Your clone dieing will also cause alot of damage so use them as much as you can

If your fed enough you will be pretty much winning all teams fights

Shaco is a great mid-late game pusher with all his escape mechanism's make use of them

And hopefully you should get a surrender at 20 or a great long game