getting a ryali staff would be like every other build, the time it takes to build s staff would get u only 80ap with the same gold u can get 2 needlessly large rods which is 160ap :P and they build nicely later into more ap in the 155ap cap or zhonya's hourglass for defense. That 2 second invulerable skill is awesome.

I thought of this but I would add a Ryali Staff to help you ulti, other than that it is just a spam build that works, xD...

It's very useful to have even lower cooldown even if you do get the bonus -15 seconds for a kill or assist. You can't use your ult again right away if you have 2 kills or assists, but with the cdr from the runes and the boots you get very close to it. People that I kill doing my 2nd ult always surprised that I can ult them so quickly after using it. Kat's ult is her main move, it doesn't hurt to be able to use it sooner. I agree with you a bit on the masteries, attack speed doesn't help a lot, but then again to get your attack mastery to 20 to get the last 5% atk bonus, there really isn't anything else to get other than the attack speed, critical damage is even worst than attack speed. But I did change it up to 2 points into attack speed and 2 points into minion dmg. Also the hp regen in the utility is not that useful either but you need 4 points in utility to get to the next squares so i put 1 point in utility hp/mp regen. As for you saying that I will fail against ad or other ap kat, it is not so. Usually people like to build items, but if you look at my build, after getting the first hat, I'm buying a few rods which at 1600gold is a bargain to get 80 ap. Other people build stuff and will likely need 2000-3300gold for the same amount of ap. If they are getting a 3300 gold item for 80ap, by then, I will have double their ap. By getting needlessly large rods first instead of building another cap, you get 160 ap for 3200gold instead of 155ap for 3430 gold. You gain an advantage of savings of 230 gold and 5more ap per 2 rods you buy to build up faster. You still have to make the caps later on but usually by then, you've already won.

CDR is totally useless in her as u got your bonus cdr when you kill and ***sist kills, atack speed is as well useless, as she is a burst skill damage hero she does not rely on AS but on pure damage, also the masterie points in health and mana regen are useless cause she does not use mana and no matter those 2 points en hp reg dont make any difference she is an ***sasin she gets in get the kill/assists and she gets out. the item choice is good but u should focus your runes in ap or magic pen or health for squishinees but as I said if u are carefull you can spend the runes in pure damage.If you go against an ad kat or pure damage ap kat or in any type of situation you will fail as kat and die and you will not be able to do your job wich is dealing DAMAGE in the SHORTEST time possible while survaving the fight. Hope this is usefull.