I tried Kata with 21/9/0 masteries yesterday, it worked pretty well, had some more dmg, but i died alot more. I can't really explain why but the 0/21/9 gives more survivability than the stats makes you think. Im gonna try it some more to see if its true and maby change my guide :)
Just try it :) and for the Liandry's Torment, its just a natural item after haunting guise, you do so much dmg with kat already at that point that 5% of their max HP doesent really matter so unless your going 3v1 or something you will usually kill them by yourslef without much problems. but since you usually go in with kata after a Team fight has started there will probably (i hope so for your sake) be some slows,, stuns, fears or some sort of CC OTHER than katarina that will make Liandry's Torment proc.
and on the first guide hextech slows ;)

I do that with 21/9... Katarina is damn hard to gank, has pretty good mobility and she can scare away people. Even 2v1 she can make people run becouse of her burst. Last hitting... just learn it before writing a guide. Weak early game??? Seriously I can nearly insta-burst someone from lvl 3.

Liandry's Torment ok did you know kat has no slow in her skills? One of your builds just make it totally useless. The other one has Rylai's Crystal Scepter but it kicks in only after the damage, making Liandry's Torment work only from your second spell.

allow me to show you the math.

you gain: 4% additional health and take 3% less damage with full tank masteries versus running 21/9/0. Kat has 1889 health at max level. Your items increase your health by 200 from torment. You would have 2089 health at max level.

2089 x 1.04 = 2173 This is your max health
2173 x 1.03 = 2238 This is your effective health - minus armor of course. Items do not come into play as we are looking at the DIFFERENCE.

Therefore you miss out on 4% CDR, 18 AP, 8% mpen, 5% increase to AP (28 AP with full build), 2% increased dmg, and 5% increased dmg to targets below 50% health. You think an extra 200 health is worth losing ALL of that damage? You're insane. An ADC will hit you for 2-3x that amount at full build.

Not bad guide but the masteries are completely Rubbish man.^^

I skip out on the 8% magic pen and all the other stuff you would get from going 9/21 points in offence to get even more early game tankiness. katarina still doesent have a good early game after the remake end all the new abilities. if you get a bad start with kata, and have a hard time last hitting you are basicly screwed since she relies so much on her items.

im not trying to be an offtank with katarina, but when going these defensive runes/masteries/items i can actually turn around ganks all by myself and jump into 2v1's, and 3v1's. it also allows me to jump in, deal dmg, and if it fail, get out wait for cooldowns and go back in. This would not be possible with a kata that goes all dmg.

With this build kata is of much more use to the team than just picking off carrys.

magic penetration is the new AP. why would you skip out on 8% extra?

also by taking tank masteries you hardly gain tankiness seeing as they scale with DEFENSIVE items which kat shouldn't be building and you aren't. 15% tenacity is a lot less than you think it is. kat usually either kills everybody or dies instantly. you do not need to be trying to go in like Irelia or Olaf who have natural damage that can get more out of being an offtank.

also, Bouncing Blades has both a higher base damage AND ap ratio AND gets a better cooldown with level. why would you not max this first?

I think you need to sit down and look at how the masteries synergize with kat. if you would explain your mastery choices in depth I think you'd see what I mean.

An ok guide. Could need more bcoding. Check guide making a guide. GUIDESEPTION.

I think yo should try to say why you choose the items you do, and the difference between movement and ap quints. Il check this guide later ;)