Greetings. This Shaco build is a idea I got while testing new builds out of boredom. Ap support Shaco isn't a popular or even a build that most people consider, but it can be quite fun and effective if you play it right. This probably isn't the best build to go but I have tons of fun with it and I normally do quite well depending on my team. First guide so it isn't going to be impressive looking.

Played 4 matches to get a picture for this.

Flat magic penetration marks for obvious reasons.
Armor Seals to help survive ganks and if they focus you.
I go AP glyphs to give that extra damage early because you won't be building AP right away.
AP Quints for the same reason.

If you need the extra cd then you could put some cd runes in but I haven't had a problem.

Honestly this was a mastery set up I picked without much thought, but feel free to use whatever you want and let me know how it works for you.

I always go with philosopher's stone first due to the sustain and the mana regen lets you spam boxes and shiv. Boots for the cd reduction and Kage's for more gold and early AP. Rod of Ages then gives you the life/mana to take your share of damage while still surviving teamfights. Deathcap gives you the massive AP to give you damage. After those items the build is really up to you. Sell the stone when you need to and upgrade Kage's if you want. Lich bane gives movement speed and after casting a spell makes your next melee do damage based off your AP. Using deceive you will be hitting 700+ per deceive. Morello's gives more cd if you feel you need it.

I use that skill sequence since shiv is your main source of damage and it is quite a nice harass especially on squishies. Box first to gain bush domination and lets you shiv without worrying about them rushing your bush. Deceive is pretty much an escape and positioning skill that doesn't need many points with this build. Grab ult when you can and use it to blow up in the middle of teamfights for massive damage.

Shaco doesn't have a way to heal his carry so I normally use heal to make up for this.
Flash is good for escaping or positioning and isn't necessary with deceive.
Ignite is nice, but I normally let the carry use it to get the kills.
Exhaust is also nice to use or let your carry use.
Clairvoyance is also a nice support spell to use if you want.

Pros
Great harass.
Easy to escape/counter ganks.
Can dominate all bushplay.
Has a low cd/high damage slow.
Can have decent dmg without grabbing minions.

Cons
Sqishy
Doesn't do tons of dmg w/o them hitting boxes.
Isn't the greatest champ to use in late game teamfights.
No heals/buffs for lane partner you are supporting.

Basically this Shaco can be great to harass and assist in a lane. Sitting in the bush harassing their ad carry all early game is a great way to shut them down. Dominate the bushes while your ad carry dominate the creeps. Main downside to this build, as with most supports, is if you have a ****ty/******ed lane partner you don't really do much. Isn't great holding 1v2, but I have had to solo top with this build and had moderate success. Fun to play. Just don't expect your team to be quite accepting when you first announce you are using this. Feel free to provide constructive criticism. If you want to be an ******* feel free just gonna be ignored.

I HIGHLY RECOMMEND YOU LANE WITH SOMEONE YOU KNOW OR ELSE PEOPLE YOU WILL BLAME YOU FOR HIS SUCK.