Karthus: Not as underwhelming as you think.
Everyone I talk to says that Karthus is a crappy champion that has most of his value in his R. However, the more I play him, the more I realize that it is not his R that you need to fear, but the synergy between his passive, W, and E. The vast majority of guides I see show full AP as the way to go, trying to achieve 800 AP or so and tons of CDR to power his ultimate... However, this isn't where his effectiveness truly lies. When I look at his kit, I really begin to see that he is really meant to be the guy that walks in first in a teamfight, lay down a W in the enemy backline and letting your E supercharged by Rylai's, Liandry's, and Abyssal, along with a bit of Sunfire Cape damage.... and when they finally do bring you down, you laugh as you use your ultimate and continue with your swirling horror for another several seconds as a middle finger in defiance... and in the fact that they focused you instead of that Jhin, whose 4th shot suddenly hurts really badly... or that Master Yi, who cleaned up, or that Veigar that just ulted the poor guy that managed to survive....
Most do not see Karthus as terrifying, but do you?
(tell me your stories or your views on this subject and I don't mind criticism as long as it is constructive... I don't like it when people say things like "get gud", or "ur garbage" without solid backing. I do enjoy explained counter-arguments even better than agreements because i can be shown something from another viewpoint and can actually learn from such.)