@Urza

k i dont really follow this build anymore so im sure what ur saying is true, lemme look at ur facts.
1. eh my personal taste, i found myself using it alot, but then again health is kewl, il try it.
2. utility bro, utility. Karthus is a farming fool. He can spend that much and get away with it, the utility is worth it more than the ap.. u sure u play karthus?
3. I really dont know why i have zhonyas on there tbh or arch lol, i usually get a banshees then zhonyas. SO i guess i can change that but its more situational.
4. no sense? i wont comment on that i dont like arguing. but ok bro.

overall, ok sure il change some things.

Oh btw ur commandents in ur thing, uh did u make those up or did u see them somewhere?

I can see many things that looks like nonsenses to me and I haven't found any explanation in this build, so I downvote until the author changes the build OR explain me why are his decisions good.

1/ Why to buy Mana Potion instead of another Health Potion? The Mana Potion could be great for low-mana characters but for Karthus? His mana pool is so high that one Mana Potion makes almost no difference. But Health Potion might give him a lot of health (because he has quite low health at all).

2/ Sorcerer's Shoes -> Rod of Ages -> Rylai's Crystal Scepter.... it gives you just 140 - 160 AP after spending 7240 gold which is definitely too low.

3/ Zhonya's Hourglass as the last item? You don't even reach it in most games and I think that this item is one of the best for Karthus. It helps in teamfights as hell.

4/ Archangel's Staff as fifth item gives no sense to me. I don't build Archangel's Staff at all but I agree with some builds which do that. But if you build it as the fifth item, you almost never charge it to max because it takes about maybe 15-20 minutes (and it can't be done faster than 12 minutes and 30 seconds in ideal case).

My third point might be quite subjective but the 1/, 2/ and 4/ are just facts.

@Kappash

.... Ok. I can see what u mean with the mana but to insult 21/0/9 karthus... have you seen it ever used? I have used it for a long time and I dominate about 90 percent of my games. It annoys me when people just say its bad without no backup.
Also the Mana issue as i said i see what u mean, but it's Very good to have mana with kartus, besides what i have is actually very decent with him, And as i said banshees is in the recommmended items just not in the main build yet i always use 1.

^^ cool :P

Real nice build use it all the time +1

Gotta try this build out! Seems like a nice build and guide for me!

yes really... If you actually read my guide You'd see why... Have you even tried it yet before you downvoted? I hate people who do that... so ignorant...
As I said I played Karthus for over a year and I tried everything... this build is very solid and Giives out a huge chunk of damage. being a avid Karthus player... I think I know what he needs, and 9/0/21 Is something he really DOESN'T need. You can use it... but He just doesn't do enough with it.

21/0/9 rly?

congrats for getting into the top three best karthus guides, you are also on the best of 30 days on the main page

@Wainb0wWaffles

Good good, try it out, it works! I actually do too sometimes as well, but Karthus is one of those char's that really doesn't need it. He has excellent zoning capabilities, which mean's you shouldn't really be getting hit by physical attacks, unless its something gay like arrow volley yah, lol. But you get your tankiness out of you
or items, and leave your runes/masteries to give you that extra boost to hit like a truck!
but i do agree with you, that armor is extremely good with squishies, It's just not my style.