Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This build for Katarina is simple to other AD Kata builds but it has more survivability.
Flash: In this case Flash is used for 2 things:
1. To run from ganks.
2. To chase down oponent and then Shunpo them.
Exhaust: I pick exhaust cuz I am using Cripple and to stop people from running away from Death Lotus.
I use 21/6/3 mainly for AD and CDR.
Importart here is to be in mid you should always get Bouncing Blade first and then just one time Killer Instinct to do more Damage with Bouncing Blade and even reduce healing. After that you should max Bouncing Blade and Shunpo.
The Runes I am using are AD Marks and Quints; CDR Seals and Glyphs.
Main thing is to max your Sword of the Occult charges really fast then comes the fun. When you finish Hextech Gunblade and Frozen Mallet you will be undefeatable.
Early Game: Remember that you have to be mid so tell others who think they have to be mid to get off. Until you reach level 6 just harass you mid oponent and when you are lv 6 start killing him.
Mid Game: You should try not to die and evade being ganked so that you dont lose Sword of the Occult charges.
Late Game: Late game is all about joining the fight right after your tank. When he enters the fight just Shunpo on someone and use Death Lotus.
Well thats everything you should know about this build for Katarina. Good luck using it. :)