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.
1) First buy Long sword
2) Then buy Boots of speed
3) When you have enough gold transform long Sword into sword of the occult, now play very carefull, try to rise your stacks, and try not to die.
4) When you have Sword of the occult, transform boots of speed into Ninja tabi, Ninja tabi + defensive runes = now you wont die so fast ( if enemy team have champs that do magic damage buy mercury threads)
5)Now buy Guinsoo's Rageblade, to increase you shunpo and bouncing blade damage
6) Next item is Lich bane, i think its core item because you next hit will do more damage after your abillity used.
7) Then buy Black Cleaver, to get more armor penetration
8) And your last item is Zhonia's ring, but if you want more health you can buy Rylai's crystal scepter
I chose defensive runes(Armor, and magic resistance0, because katarina is very squishy, runes and Ninja tabi will help her, stay longer in the battle
I chose exhaust and heal
Thats all, i hope this Katarina's build helped you, to cut your enemies into pieces...