Talk:Karthus/@comment-1920550-20140728023950/@comment-12314620-20140730212110

Karthus selling point is one of the most powerful lategames in the game, which is the result of his huge dps and his passive which guarantees you damage in teamfight unless you die out of position. His ult damage on early levels isn't impressive, I give you that, but it's enough to win most all ins if both fighting partners are ~even in gold and somewhat equal in skill. A skilled laner might just force an all in upon seeing the ultimate animation.

Karthus isn't easy to abuse when behind. His range enables him to farm safely from a distance, his dps makes it easy for him to farm jungle, his dps makes him great for taking objectives even when behind and he will never be useless in teamfight, since his passive quarantees him 7 seconds of unrestricted spamming and creating a huge dangerzone to opposing team.

Karthus is hard to play and requires patience in lane to do well against decent opponents so that might be the reason you don't see good Karthus players in your games. He doesn't have many hard matchups since his Q allows him to farm in relative safety while E passive rewards lasthitting with mana. However his global presence is a major annoyance (since there's literally no place in whole map where you are safe against Requiem) and forces 5 players to adapt their playstyle to Karthus simply by existing (all ins become much harder, earlier b:s because of the threat of Karthus ultimate, lategame barons after teamfights are much more risky because ultimate hurts a lot and damage is amplified by baron).

Finally his manacosts are usually manageable with only RoA, Q spam and placing you wall are your most important jobs in teamfights. E is practically only used when you have to kill a diver quickly, plan on suiciding in the middle of their team, are forced to fight close range against a target you can't focus for whatever reason or several players are diving into your team. You take Exhaust as Karthus, and since you usually position yourself close to your marksman you can make Assassins regret trying to go for their targets (Exhaust usually prevents assassination and standing in Defile while being under Q spam hurts a lot).