Or does the Nexus pixy dust make it so that they don't feel pain?

It seemed like the summoners winced whenever their champions were hit as well. Do they feel any sort of pain?

Mundo Trolls as he pleases.

And no they only feel the pain of vomit pushing up their throats when they see lollipoppy. As for her the pain she feels is that she was born.

Prob yes, since sions pasive is feel no pain.

Considering Sion's passive, I'm going to have to say the critical existance failure present in the gameplay will probably have to be just brushed off with "Being virtually incapable at low health would really suck.".

I hardly thinking having say...Garen slicing you in half is not going to generate feelings of agony. I'm pretty sure experiencing injuries or death are still darn uncomfortable.

Well, they don't care... They have unlimited respawn ability.

After a while anyway, the sensation of pain would matter less and less. If you get used to it then it doesn't matter any more and it becomes natural.

So if you live with pain for a long time you begin to not notice it.

Wait, so if champions do feel pain... why do people feed o.o

Sion "Feel(s) no pain" ;P