Hi I'm a newcomer to GD and I was thinking about this, I'd really like to share my insight on a champion I have dedicated a lot of time to.
Karthus is too under powered and I think his skills need a total rework.
So here are some of my ideas:
Karthus is now melee and jabs people with his stick
Everytime Karthus casts a spell his next basic attack will jab the target so hard in the knee they will be stunned for 2 seconds
Karthus body slams his target doing enough damage.
Karthus summons a huge tornado in an AoE in front him that sucks all nearby champions into it and as the targets are spinning he pokes each target in it making them bleed for 10 minutes and makes them dizzy for 20 minutes (they walk opposite of where they click)
Allows Karthus to summon his girlfriend Hanturegagayache. Hanturegagayache bites her lip and says I love you. Then fades away giving Karthus attack speed.
Karthus throws his staff on the ground and starts using his kung fu abilities to help him fight for 20 seconds. (Karthus now punches and kicks targets) When he is in this Kung Fu form nothing happens ha.
"Do you... feel a chill... because I don't"
"My brother is Teemo... YES!"
"Their pain... needs a bandaid"
"I desire to poo"
"I carry scissors... Ooh"
"I wish to poo!"
"Our lives are awesome!"
"I'll put you... in my book so I can stare at you and kiss you and have secks with you!"
"Two ponies were moving across a field... I shot one"