I have tryed most of the summoner skills and these are the ones that I find most helpful with this build, your attack speed will be at or close to the cap for quite abit so I like to keep the enemy at bay. The 1st skill stops them escaping and is also usefull against high damage chars, that may start to try and kill you. Ive took the 2nd skill for people like fiddlesticks, it just helps to scare them and generally stops them playing at there best as they are scared that you will decive and a ignite them. Which means reduced healing and a large chunk of there hp taken.

Although I do like some other skills, one that I feel is seriously underrated is heal. With this you can over power people once you, Ive had situcations where several people attacked, when you use your clone your hp will soon go down, heal adds extra damage to your clone aswell helping to keep it alive for longer which means more kills.

What the hell why Sorcerer's Shoes ?
Personally I think they are a great item because they add movement speed and help Madred's Bloodrazor. I take either these or Ninja Tabi either item helps so it normally depends on if I need the extra penetrasion.

Malady
It adds attack speed which helps move towards the cap not only this but it adds 20 magic damage this will make the high attack speed deal more damage. It also packs a resonable amount of ability power which boosts the damage from some of Shaco's skills. The reduction in magic resistance also helps bloodrazor achive the maximum damage.

Phantom Dancer
This adds attack speed which is the main focus of this build and gives a nice critcal strike chance. Meaning the roughly 1 in 3 attacks will be critical.

Sword of the Divine
More attack speed and a onhit effect. Meaning that you can rip though enemys like paper.

Hextech Gunblade
I only build this as my final item Im not a great fan of it but its something to build my Vampiric Scepter into. The attack damage and other extras are still help full though.

Madred's Bloodrazor
This weapon will just destroy a enemy with in seconds. It gives armour that helps you take a bit more damage, as well as attack speed and damage but the passive is where the real power comes from. With Shaco maxed at 2.5 attacks per a second he can cause some serious damage. For example he attacks someone whos has 3000 hp, within 2 seconds he will have done 600 damage just of this passive.

Carrying this over to the ful build you see the pure power that you will have to destroy everyone. Just off passives alone.
If a enemy has 3000 hp in 4 hits (1.6 seconds) you could have done,660 damage just off passives you still have your attack damage to add to this and the fact that at least one of these attacks should be a critical. And as if this isnt crazy enough you can use your clone, you destroy people within seconds and have decive to escape so that nobody even kills you.

And if jax shows up to ruin you day you can use your swords of the divine active to give you 5 seconds of dodge free attacks. Which means jax dies.