Only diffrence in your items is that you wont use pen boots.

Also i almost never use zhonya, it is situational item.

Katarina dmg is so damn op in right hands that she doesnt need ignite and any points in ferocity. As Kat with ghost your job is to be in right place in right time, you can help anyone even if he is half map away from you. Also ghost Makes you able to dodge everything in teamfights. You have to roam, of course you can try to kill your laning opponent but your main job is to be "second jungler" so you can even cooperate with your jungler with ganks. Ghost gives you possibility to escape even worst situations, also you can catch anyone on the map with that speed. Possibilitys are endless.

Also im One trick pony katarina since s3 any questions? yep i know what you wanna ask:
im plat in s6, and aggressive katarina is the only good katarina.
oh. and i made a video. im not good in choosing good scenes but rate it what it deserves :)

Do you have any proof that this works? yep, here u arrr:

Play Video