Katarina and her Ult.
I love it, it's amazing, it deals incredible damage.
But it needs counterplay beyond "Stun me before you take 2 ticks in .5 seconds with .3 seconds latenc-TOO LATE"
Why not have the damage ramp up over the duration of the spin? Still deal the delicious total damage, but give players a chance to GTFO and live. It would also allow her to keep her burst, as her later daggers would be even more threatening.