I'm just sad that there are literally so many counters to
ult.

Feels like every time I play Karthus in draft I just get counterpicked to oblivion.
I was in a beginner bots game. I didn't fully read the spell, but I knew it did damage.
So I walked up to Malzahar bot sitting in mid lane, used my ult, then started trying to hit him with my Q's and E. He dodged most of the stuff and got away after killing me.
I didn't even realize my ult affected the whole map. I just felt defeated because it seemed to do so little damage, had a long cast time, and had a really long cooldown. :c
When the Pool Party Party IP weekend rolled around though a few months later, I decided to get Karthus and try him out again because I was moderately sure that his kit was actually cool and I misused it in the bot game. I'm glad I did--he's my favorite mid laner right now. (Favorite champion, actually.)
Best ult is when you try to kill chump that run away with low hp and you get double or triple without actually seeing any of your victims.
You j ust made me really want to watch the harry potter series again
then you realize the whole enemy team had 
And the entire team collapses inside a
ultimate so you get nothing.
Hey look at that Karthus, your ult is even more useless.
My first Karthus ult was a double kill.
Karthas ult, Slow telegraphed, and easy to itemize for....
Better nerf QSS'ing Zed's ult!
What's the incantation again...let's see here...Oh right! R!