Hi Mobafire User!
I've been playing Karthus for a long time and I felt like making a build for him. Many people think Karthus is a noob champion, because of his ult, but I find him funny to play and great at good hands.

Pros
- Great Farmer.
- Good Harrasser.
- Massive Demage, even dead.
- Hard to Gank.

Cons
- Low Mana
- Focused

HARD
Hard heroes to face in your lane:
If you stay behind creeps, his stun won't hit you. However, his burst damage is way higher than yours, so try to gank or becoming fed from killing other enemies with your ultimate.

- She is really annoying, because it's hard to place a wall on her, due to her blinks. She can get close to you, do damage and get back, and you won't be able to do as much damage on her, as she does on you. However, keep yourself behind creeps and farm with Lay Waste.


MEDIUM
Medium heroes to face in your lane:
Anivia can really be a pain in the *** for Karthus. Anivia has more damage than Karthus early game and more survivability when her egg is up. Play safe and farm well, but I wouldn't recommend that you try to kill her 1v1. If you have a jungler, get him/her to gank Anivia. See if you can get the kill in order to be fed, so you have an advantage against your laning opponent.

Against Teemo you should do fine, because his blind, won't affect you that badly. Just throw a wall at him and spam your spells at the little dude. This should keep him off your back. When he has mushrooms you might want to get an oracle, so you can destroy his shrooms. It will make it a lot easier to gank him and piss him off.

She can be pretty annoying, but you can stay behind your own creeps and farm. Just make sure, she doesn't hit you with her stun. Try to harras her and see if you can get a kill at lvl 6. It's really just about avoiding her skill shot and to farm better than her. Try to make her run around a lot, by spamming bubbles at her.


She is devastating when she hits level 6. Care and try to gank her to get an advantage over her. Just try to far, but stay safe. Keep track of her passive, so you know when to have flash ready to escape her stun.

He is a really strong pusher, so you might need ganks on him as well. When level 6 he can shut you down, so be very aware of your HP, so his combo won't necessarily take you out. Perhaps rush Catalyst the Protector for more sustain, instead of Tear of the Goddess, cause he will harras you and keep farming. A tough champion to face, but simply try to farm and hope for an opening to kill him.


EASY
Easy heroes to face in your lane:
Ashe is not that big a problem to lane against. Everytime she tries to get close to you, throw a wall at her and spam bubbles. You will also be able to farm better in most matches, because you have Lay Waste & Defile. Just care when she turns level 6 and had stun. Try and get someone to gank her, so she can be denied as much as possible. This will give her a hard time as a carry.

Just constantly harras him with Lay Waste, so he has a harder time last hitting with his Q.

Just play careful and try not get hit by shurikens. When you & him hit level 6, Kennen might use ult on you. Also try to outfarm the ninja, so you have an advantage in your items.

She is a long range harrasser, but watch out for her autoattacks as well. Keep your distance and farm the best you can.

Mirror-lane is fine, especially if you have this build