I feel like Karthus is a bit underpowered, I main him and it's a lot of work to make him function in game on a regular basis. Not to mention I constantly have people dodge when i hover him in champ select. He is in weak state but he can be strong if played right. Maybe a buff with the upcoming Light Bane skin will put him where he needs to be. 
Remember the Reaper!
Karthus is underpowered because of mobility creep. I think he needs a small buff to either his Q's delay duration or to make his Wall of Pain apply the Grounding effect while they are slowed.
he isn't a reaper (unless it is Grim Reaper skin), he is Death Pope
Karthus has an easy time snowballing, and tbh is one of the scariest lategame midlaners. 2 Q's on the enemy adc and they're dead basically, he's not underpowered. All he really has to do is flash into the enemy team with his E up while your tank goes in, wall the backline and hit them with a barrage of Q's and ult when he dies or something like that. He's really strong, but not played a lot because people think his Q is easy to dodge. If you don't buy boots on him and go pure damage, if you see anyone that is less than 60% health then just ult and they'll die.
[{quoted}](name=Pale King,realm=NA,application-id=3ErqAdtq,discussion-id=yXL58WLz,comment-id=,timestamp=2016-10-24T19:47:40.045+0000)
I feel like Karthus is a bit underpowered
He isn't. He's had consistently high performance rates for a very long time now.
