Suggestions and a complaint.

First the complaint. Sion. For a guy with that much utility, he does a ridiculous amount of damage when building full tank. But I would like to specifically mention his q. It may vary between skins, but at least for the classic skin, his Q visual does not seem to match the actual area of the knockup. Both playing him and playing against him, people who appear to be entirely outside his Q visual are still being affected. A visual tweak showing the AoE more accurately would be a big help to playing against him, and players learning him who haven't mastered exactly where his Q actually ends.

Suggestion time. For Illoai, one of her weaknesses is that she cant really hide in a bush. Like Sol with his stars that are visible when he is hidden, her tentacles show when she is around. Most of the time that doesn't matter much, but if hovering the mouse over her passive skill icon could show a range indicator for tentacle activation, or at least tentacle spawn, that would be helpful.

Before Dynamic Que, a player in que could click on a champion and see the champions abilities and tips page. For those who have played the game for years, this isn't needed very often, but with well over 100 champs, new champs added every several months or so, and some champs going in and out of style leading to certain nuances of lesser played champs to be forgotten, even oldtimer League players could occasionally make use of this feature, and I think it really helps reduce the barrier to entry that new players face when trying to get into a game with so many champions and skills to learn. Rather than hoping the enemies only play champs you know or spending hours going through the champion section in the client trying to memorize every champ and their ability kit in an effort to avoid facing a champ you have never seen, getting completely stomped and reported for intentional feeding by a team with no patience for a clueless noob teammate, being able to look up the champions picked in client is a small but very handy feature I strongly recommend bringing back.

Lastly (for the moment), please do something about the way Grievous Wounds just wrecks certain champs. With the Mrellonomicon changes making it a core item on most ap champs it isn't even really a niche pick for mages and even some supports. With Executioner's Calling only costing 800 gold, ignite, and a couple champs having it built into their kit, it isn't exactly hard to come by for tanks or ad champions either. Since GW is only really an issue on champs like Mundo, Volibear, and Swain that use the sustain to tank in fights as a front line initiator or as a damage sponge, you will find these champs in the middle of team fights, not split pushing or jumping in as an assassin and running away. This means that even one enemy with GW can shut them down pretty reliably when they need the sustain the most. GW from Morellonomicon only takes affect below a certain hp threshold, but the other GW sources affect healing at all HP values, and with the buff from 40% to 50% penalty, the ease of proccing GW in a fight, and the many, low tradeoff paths to getting GW for your team, playing champs like Mundo, Swain, or Volibear feels consistently weak, like these champs are playing with a gimped kit. At level 1, if you can keep GW on him the entire 12 second duration of his ult (which unless he runs away right after casting it isn't very hard), Mundo hardly makes back the life he spends to cast it. I don't really know what the best way to address this issue is, maybe revert GW back to 40%, but there are some champs not really worth playing in the current GW abundant climate.

Edit: I forgot to mention, Garen's ult blows. It just stinks. It is simple and direct, which I like, but it is really only good for killing people, so its situational, has a silly long cd and short range, does physical damage so it can be mitigated, but has no scaling (yes I know it scales off missing hp, but that just makes it an execute. Considering how easy it is to get enough armor to really cut the damage, using it any other time just means it wont do any meaningful damage at all) so there is no way to hurt anyone who builds armor, and did I mention the cd? Other champs have executes that are not as confined, ie Darius (his ult scales off ad, plus chains), Cho'gath (lower damage but its true damage, and it scales, and gives hp) even Volibear and his execute isn't even an ult (yeah its not as strong but it also gives attack speed and, again, can scale. And it has an 8 second cd!). Yes there is also the villain mechanic, but I've never felt like that was particularly impactful. Please give Garen some love. Nothing outrageous, maybe a cd drop at all ranks? Or change the numbers and swap it to true damage? Either that or make the villain mechanic more meaningful, like hitting the villain with his Q procs a .75 second taunt on a 10 second cd or something? Something....