All in all AP shaco is a troll build, but puts out incredible damage. I usually go mid and help my jungler leash blue with a few puppets. In lane, harass often with shivs/puppets and try saving your decieve for escapes/engages. In team fights, your job is to focus the carries because your burst from your shiv/deathfire can burst a carry down to no hp at all! Stacking boxes is always fun. A good place to stack boxes is on the route of the enemy jungler. This way they will be pressured because you are often distrubing them.

For runes I go 9 magic pen reds, 9 flat ap yellows, 3 cd blues, and 6 ap blues.

For masteries, I go the basic 21/9/0. Full ap on the 21 offense tree. Using these masteries, your boxes should do insane damage as will your two shiv.

For items, I build standard AP items. Why deathfiregrasp you ask? DFG is very important for shacos burst damage. For example: if you stack boxes, and an enemy walks into your boxes, you would immediately use the DFG active on the enemy. That should guarantee you a kill.

Ignite/Flash I've found is the best summoner spell combo for shaco.
Ghost/Flash is also good summoner spells to use, but I prefer using flash instead because of the quick chase.

Pros:
1.EXTREME damage with or without runes
2. Very mobile when it comes to map control.
3. box stacking is incredibly fun, and can also win team fights.
4. Clone exploding does alot of damage
Cons:
1. No sustained damage after initial burst.
2. squishy
3. potato
4. Melons.

A good shaco always knows how to move around the map correctly. For example, in a team fight you don't want to automatically jump in. You want to send your clone in first, and let the enemy waste all it's cooldowns on it. After it explodes, you should rambo in and focus the enemy carries/squishies.

Box box box boxes everywhere! A good shaco also takes his/her time and sets boxes in a specific location. Setting 3-6 boxes at an area can guarantee a kill when an enemy mistakenly walks into it.