^ This is a big problem with Riot's mindset, imo. Let me use Noxus as an example.
Noxus is a nation that has waged at least two brutal and bloody wars of conquest against innocent nations, solely because Noxus perceived them as weaker and easier to conquer. In doing this, they enlisted the help of assassins to murder families, thus "pacifying the barbarians", they enlisted the help of Singed and Zaunite melters to melt alive entire villages of innocent people, and experiment on them, as happened in Master Yi's lore. They butchered Alistar's entire family, captured him, and forced him into the Fleshing, which speaks for itself. Xin Zhao found his way in there, too. Let's see... Annie and her family were forced to flee for their lives for daring to oppose the conquering monstrosity that Noxus was becoming, and it's generally believed that General de Couteau disappeared for this same reason. They are obscenely racist, as we saw in the case of Veigar.
Can someone please direct me to the gray in any of this?
I find it very hard to call any Noxian champion a 'shade of gray' except Riven. Why? Because, let's assume that the vast majority of Noxians had no idea what kind of horrific war crimes their assassins and Zaunite allies were committing. After all, very seldom do the citizens know of what their own soldiers do. But, lore-wise, several years have passed. Everyone knows what Singed did, everyone knows what the assassins did, everyone knows that pretty much every political leader in Noxus would be hanged like Saddam if the Geneva Convention existed in Valoran. Yet, what happens? No Noxian defects, no Noxian has ever expressed even the slightest shred of remorse. Katarina, whose own father is pretty much guaranteed to have been murdered for opposing the Ionian campaign, does not defect, does not go into exile like Riven, NOTHING. Hell, in one of the JoJ's, she mentions that Noxus was doing Ionia a favor and they should be thankful.
If this is what Riot thinks is 'shades of gray', I'd hate to see what they think is evil. Riven is the only Noxian that has been shown to have any redeeming qualities whatsoever. I guess the stance of Riot is "yeah, but so-and-so Noxian isn't really a bad guy, per se, he just values personal achievement as a means of excelling in society as opposed to bloodline and heritage." No, Riot, that does not excuse melting innocent people, experimenting on the survivors, forcing the survivors of that to fight each other to the death in front of a packed stadium of Noxian citizens, and then telling the world that Ionia should be thankful for it.
Noxus is evil.
And Syndra, while obviously not that bad, is no 'gray' either. "I'm not a bad girl, but I killed my mentor for daring to teach me to use my powers responsibly", that doesn't fly.