How viable is Karthus

or nah?

ok, Ill just go...

hes good but hes weakness in early game and laning if you get to l8 game or even get some items in the midgame u could do great just farm safely cuz karthus laning is terrible playing him is to be just patient for that sweet l8 game

While he has some really good poke and power (plus his ult, which is always a huge threat while it is up) he also has some big limitations, such as only one real CC (the slow on his wall), the average squishiness of a Mage, and no mobility whatsoever.

Also his main form of poke has a very noticeable delay that most enemies can just walk out of by the time they get boots.

He's an ARAM god? I've only seen one karthus mid in the past month, and I annihilated him by ganking for my mid kassadin. And this was after patch 5.4, with the kass nerfs.