Since it hits random champions in the area around him, does that mean its an RNG value that determines what champion gets hit?

I just finished playing Kennen and i noticed late game when i charged into their team, it would strike completely random champions. I was hoping each time that it would hit the enemy Kog Maw, and it always seemed to focus the other champions instead.

Would love if we could change it to a variable, maybe lower health targets get striked first?

What does RNG mean?

random number generator

Nami and Fizz are more likely to take damage, wheras Malphite is prioritised last.

I would assume it does. The same with Kat ulti

Crit chance raises the chance