Nah not good.

^

One more thing. you said i dont build AA wich is a must for kath. i will say it is not a must, i will say its a must for suicidal kathus yes, but if you rush AA you wont get that much mana and therfore less ap of it. and i you read my whole guide ( wich you probably dont have) you can see i say something about AA and i it lays in Item section, but i dont buy it if it isnt a veeeryy long game and it rearly are longer than i can get evyrthing i use to buy. You can Buy tier of the goddess instead of hunting guise but i like hunting guise better so that means i put it into MY build, its personal preference.

1 thing.. Clairvoyance is a epic spell..for many ******** reasons..its a anti gank spell, you can chekc baron/dragon or even check who you are laning against! and i wont say clairvoyance is a support summoner spell because of its meny diffrent in use. you can use it for supporting yes but you can also destroy ganks for your teammates. example you see shen go trough mid and watches he go up for a gank you your teammates. you can pling and pop clairvoyance in the brush for extra attantion on where he may is. Defile is a awffull way to kill minions. use your lay waste for farming minions and then if your enemy is getting to close you use defile for getting him low or a kill, but if you use defile to kill minions you wont have full mana cause it cost ALOT of mana per sec and you will be low of mana evyr time you use it for killing minions. therfore if the enemy is a good player he will atack you when you are low on mana. + why do you say my Laning section is 100% wrong? evyrone have a own playstyle! you can say you dont like it and you will rather use defile but dude, dont be that rude to say its totally wrong, cause it isnt!

You should probably read some other Karthus guides and check what they say.i have read one of them and they agree with using lay waste instead of defile.

Next time you comment on something think of your style, and then think that they maby have other ways to get minion kills/ kills. Use a little bit of the brain to think "maby they like it that way" or "hmm, i could try it out and check if its better than mine"

-Amotherlover
This is not my build lol(and neither do i play karthus much, this is based my experiences with the game) but i would still like to say something, first of all about the archangle's staff. sure it is good in a way but rushing it will make you weak early game and it does not give much ap early/mid so you can rush tear of the godess and build to archangle's late game because it gives much then.

And about the runes, thats personal preference really. but he could have wrote more options

And for laning section, have you even laned against sivir? even tho her boomerang blades gets diminished returns after hitting minions it sill does 70-100 dmg atleast at around lvl 9. and a good sivir would hit you with it for full dmg sometimes and that is around 400-450(depending on your armour) and it is not that easy to dodge. i play sivir, and a good sivir beats karthus eeasy.
her spell shield makes her harder to harass and you wil make her harass more, but why did noone mention riochet? if shes good she will make it bounce to you and that means she gets longer range in a way.
and dodging enchanted crystal arrow, is not that easy. a good ashe will only fire at the brief moment when you stop a little bit.

And about clairvoyance its a good spell with 42 sec cd. if you need to ulti someone at a tower you dont see use that and see if you will hit or not. get the point? but its personal preference to.
and farming i dont know anything about so meh :)

-1

Im sorry to say there is a lot about this build i disagree with. Starting with your core build. I noticed you don't build a AA (Archangels Staff) which is a must for Karthus. After you cap the mana boost, you will be sitting there with well over 2000 mana end game, and since your playing Karthus, maxing this will take no longer than 5 mins. Plus with it's AP passive, you will gain about 100 AP from just this item alone. Which in turn gives you enough mana to never need blue (unless you really are in need of the CD). You claim to have survivability in this build, and with that you should be building a Soulstealer. With the RoA and Rylai's, you build enough health to be able to stack and not worry about being squishy, and you must also remember Karthus' passive, so even if you get focused down in a teamfight, you will gain stacks for assists and kills after death anyways, making a Soulstealer a good item as well. The Haunting Guise is a useless item for you, as you already have MP runes AND Sorcerers Shoes, plus you should be getting a Void Staff so even if their tanks build MR, you can still do crazy damage to the tanks.

Looking at your runes, you need to use AP/lvl instead of flat AP runes, because at lvl 5, your AP/lvl are already stronger, and keep getting higher.

As for your Laning section, I don't even know where to start. 1) if your gonna put Sivir in there as a hard person to lane against, use the right reasons why. Her Boomerang blade deals less damage as it passes through enemies, so if your behind your minions (which you should be), it wont hurt you much, plus you should be constantly moving so you shouldn't ever get hit by it anyways. You also forgot about the main reason why shes "hard" to lane against (even tho I find her easy), and thats her spell sheild. If she used that and u hi her, she gets more mana back and can harass more. 2) Ashe is not that difficult to lane against either as long as you know what your doing. If you stay behind the minons, she will never hit you with her Volley, and if you see her running at you with her Frost Arrow up, just simply hit her with a few Qs and your wall and watch as she runs for her live. As for her Ulti, just keep moving in big and dfferent patterns, that way she can never predict where you are going, and miss when she tries to get you. 3) Morde is not that hard to lane against early game because he is very squishy. Just harass ihim and starve him from exp by only last hitting while focusing most of your time keeping him away. Morde is only good when he has items AND an enemy minion wave.

As for your Summoner spells, thy are ok but there are better. Flash is nice, but I personally like Ghost better because it lasts longer, therefore giving you more distance to work with. Clairvoyance is NOT a spell you should ever have with Karthus. That spell is for supports, plus you need to worry about yourself as you are super squishy. If anything you should put either Ghost or Clarity with Flash. And fyi just because Defile gives you a SMALL amount of mana back, does not mean you should rely on it.

And last but not least your Farming section is 100% WRONG. You should be using your Defile for farming minion waves as it is 10x faster and you still end up with full mana.

All and all I have to say this build needs plenty of work. As a guy who has mained with Karthus for well over 7 months, this build does not work.

This is a good long guide and i like the build.
most karthus's just stacks archangle's or is very glasscannon but with this you can survive a little and still do good dmg.
and i really love the clairvoynace