Not Updated For Current Season
Runes are pretty straight forward red magic pen, yellow I get health its just more reliable than dodge but if dodge tickles your pickle than you can chose that instead, blue is CDR.
I go with ghost and Ignite,ghost helps getting moving to places faster and ignite helps you pick off anyone that escaped your ult. Both exhaust and ignite can be cast while using your ult with out the cast being interrupted so keep exhaust in mind as a spell too. Other spells are just simply not efficient enough for Kat, flash is fine but you have shunpo so again not that efficient everything else is not good for her.
Hybrid Item Build
This Build is by far one i had the most success with its give your early game burst and late game sustained DMG. I usually get my boots out of the way and my first item is Rylais the reason why I get Rylais first is HP the slow and AP its has everything kat would need for the whole game. after Rylais i work on a Blood thirster and then a Hextech gunblade the spell vamp from it and the AP and AD is great plus its use is pretty decent and good for ganks. realistically your prolly gone with your game by the time u get to thirster or hextech unless your pubstomping or just straight up a long game. In the cast of a long game here my build;
AD Item build
AD is WAY more easier since Kats changes your never going to waste and AP item ever now as of a AD build....stack Thirsters. Seriously Blood Thirsters are Kats best friend for an AD item. I normally get my boots once i do i get a BF sword and then work on Hextech. Why Hextech? spell vamp and good for Kat everything she does heals her and it makes your Shunpo a little bit more powerful since its most not going to be that strong in an AD build. then I complete Thirsters and start another Thirsters. If things are not going well build a DEF. item i usually build a banshee's or Rylais (the HP and SLOW is amazing on Kat). note this AD build is a bit hybrid-ish.
an ideal build is for a real AD build is;
thirster x 3
AP Item build
Kat can have some nice burst with AP too her build can get tricky in ad since there are items that are useless for kat. You start out the same Doran's Shield or if you feel boss you can get a Elixir of Fort and 5 Pot's, the first item you get is also Rylais once again its really good for Kat early game then next item you want is a Hextech gunblade it gives you the survivability You can use the spell vamp really well and you get extra survivability because of it and a little bit of AD too. After Hextech you need DMG so Rabadon's Deathcap is something you want Asap it also give u additional increase to your overall AP by 30%, next you want a void staff the magic reduction and the AP you get is really nice for Kat also if you any some MR while your at it instead of a void staff an abyssal scepter is really nice. by the time you work on your Deathcap or start a void staff/Ayssal scepter the game should be ending but if you need a 6th item for a long game get another deathcap more AP equals rape with her ult.
Differences between AD and AP
This question now is more confusing actually answer why? simply put everyone has there own preference with Kat swearing by AP or AD builds but honestly hybid is the best since your ult does AP + AD and your q is also AD + AP so it would be a waste to go strictly AD or AP since your not getting the maximum dmg out of Kat its either your ap u can burst have a ****py Q and be useless late game or go AD have E as an escape ability and do medicore dmg the whole game.
- More damage output than AP
- sustained Damage throughout the match both with her abilities and her auto attack
- make her harass game really safe and very good
-Expensive to build
-Her shunpo is more of a ganking tool or to target a enemy to ult
-her shunpo has poor damage
-burst damage with her ult
-shunpo is basically a nuke
-can be effective even early to mid game game
-shunpo although hits really hard puts you in a bad spot and you can die since your right next to the enemy, its not a good harass tool its more of a ganking tool at this point
-Kats auto attack is useless you do nothing with it
-Kat bouncing blade is also useless you do little damage with it and your harass is poor
-early game your effective because your burst is more potent due to your enemey getting thier dmg and def items but late game can really drag out Kat's ult and make so your not doing that much dmg unless u get assist and ult spam
Playing with Kat
This is the fun part ^_^ Kat is not a hard champ to use to be honest, but she just like every other champ needs to be played right. Play Kat as if your dancing and what I mean by that is always move and try to move unpredictably at that, its important never to stay still with Kat. When you are in a 1 V 1 with her you need to choose your battle's which means you want squishes they are pretty much Kat food for her(no pun intended =P), champs like Yi and Warwick can be tricky you want to take a in and out approach with them so that way there not auto attacking your face off. team battle's however are more important you want to harass as much as you can with Kat before the fight actually starts, once its does its really really important that you shunpo in and ult at the right time and that is pretty much when everyone else jumps in the fight which means your last to get in the fight, Kat is more clean up than anything and she makes sure champs die.
During the match you also want to make sure your ganking whenever you can. Kat is a really great ganker and starting out early gives her an easier time getting her build started and get the optimal items you need, make sure if you go off ganking that your lane is covered or the enemy champ in that lane is dead, also start ganking atleast at lvl 6.