shaco is not good at the start but when you get deceive to lv3 , two-shiv poison to lv3 , ultimate lv1 or higher and have B.F. sword and the infinty edge you can easly kill enemy champions beacuse you have 1.3 in speed and over 100 in damage. it is better if you also have the trinity force.

see another build :)

shaco is a verry good ganker try to look for champions with low health . shaco is not the best team fighter because he get focused verry . so he is better in the jungle alone 1v1. but if you have a team fight use your clone it can save your life. and give you a lot of kills

take all the attack speed runes then you only need 1 phantomdancer

i use offense masteries , and utility masteries. i use the offense masteries beacuse shaco is a offensive champion so i have verry offensive masteries

well when you are fighting a champion when and he is starting to have low life and he/she is going run back to it's turret then use your ulimate
to protect yourself the turet will attack your ultimate and you can trow a two-shiv poison on the champion then use decive to finsih him off. if not use ignite. if that fails run into a bush and plant jack in the box in front of the bush . then recall back to the base.
if you are in the jungel use first decieve then attack him and use two-shiv poison to slow him and use your ultimate to attack him if he tries to escape use decieve and ignite him and trow annother two-shiv poison. then finish him off with flash