Fair enough!

It works great for me, and I've done a lot of testing.

It seems to me you get AP realy late with your philosopher stone, plus with an item like the fiendish codex, you'll not make you're Rabadon's passive effective. Andyour Rod of Ages is realy late to be effective to. If you're a realy good player, and do some good last hits, it might works, but I don't think that's a good item order. And if you do some good last hit, you don't need some gold item.

I disagree with the masteries too. Yes defense is nice, but as you say it, Karthus need a good mana regeneration, so why not taking Utility masterties ? You already got your wall and your harass to keep you safe.

Otherwise, your build is done nicely, that's sure.

Sorry, but that's a -1

Thanks guys!

I'll make the changes; agreed.

^ forgot to vote

Pretty nice guide, but you may want to check out your skill sequence...looks like one (or 3) too many Lay Wastes. But otherwise, good job!

It's a pretty nice guide overall.

I give it +1, although I think you should mention that in late game people can sell the philosofer stone for zhonya's hourglas aswell. It's a good item , gives good HP and it can get you out of messy situations. Also the + 45 armor is pretty good considering you don't have much armor to begin with .