This build is great for critical damage and this build is great for ganks as well notice i do not use consumables why? because you dont need it just keep your distance hug your turrent and feed on minons you should not be pushing with this champion untill mid to late game (obviously because your way to squishy)

if you have played with this champion notice that most of your spells do not mainly focus on the champion this is why you need critical dmg to show off your splash dmg and to keep champions at a distance. Spell vamp also applys some more Ability Power dmg with a little bit of life steal so you keeping your distance is good even when you die your passive attack rise of the thorns allows you to hit the champion one more time which is why you need trinity force and hextech gunblade :3 other then that other items are for ability power enjoy!