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.
As Katarina, you make an amazing solo laner. Take the solo lane and use the range of Kat to your advantage. Theres no mana so just keep throwing your blade. When engaging against Warwick or Mundo I'd advise using Killer Instincts then throwing Bouncing Blades at them to cut their life steal/hp regen. Also when entering a teamfight (after your tank) use Killer Instincts then Shunpo into the fight then use Death Lotus. Good luck :D