A list of Toxic Champions for each lane
Mid lane:
Yasuo: This champion pretty much invalidates ranged harass, beats most melee matchups unless the player playing him can't space at all and just by picking him you auto win laning phase because of his borderline infinite dashes, low cooldown AOE (in a line) Q, spammable knockup and aforementioned invalidation of ranged damage and general poke (shield+Windwall). Then he picks up crit and he wins against almost every champ in the game provided the player isn't an absolute chimp, and even if they are Yas can just auto you to death with crits+Conqueror.
Zed: Pretty similar to Yasuo, only he's like the Leblanc of AD assassins, he's insanely safe and possesses insane damage. He's pretty much THE "outplay" champion who doesn't have any "bad" matchups, can win against any champion in the game due to his kit's design and he pretty much doesn't have a skill ceiling in a similar sense to Riven. Then you factor in Lethality and you quickly realise that the moment he even picks up a Dirk he can chunk you for ~50% of your HP upon hitting a Q+E with Elec from W. Sure, armour works wonders, but Lethality is cheaper than armour and armour items don't exactly give you damage. Oh, and he got overbuffed and still hasn't received any nerfs since being overbuffed, so uh yeah, that happened.
Katarina: Her rework removed most of what made her fair, besides the general speed. Tbh Gunblade just needs to be removed, that item makes her broken.
Leblanc: She shouldn't have been reverted. Too much point and click burst, really good early game cheese and chain's tether range is still fundamentally broken despite Riot having over 9 years to fix it.
Talon: Rework made him braindead, broken damage (early-mid game), low to no counterplay outside of laning.
Ahri: The Ahri of mid lane lol. Far too safe and effective.
Mid lane's "toxic champs" are pretty much all assassins (who would've guessed). The assassin update broken Kat and Talon though, so I'd be down for reverts tbh (or at the very least item reworks).
As for Zed and Yasuo, those champs just need entire kit reworks. I don't know why Zed didn't get reworked during the assassin update, but hey, there's still time to rework him. Yasuo also needs a rework, or at the very least significant changes for fairness, particularly pertaining to Windwall.
Jungle:
Hecarim: Runs you down with E and then spams Q auto until you're dead. Even if you dash away he can just R. This would all be semi-ok if his clearing sucked, but it's actually really quite good....so all in all he's toxic. He's an assassin with bruiser tendencies, he NEEDS a rework to be more like a bruiser.
Karthus: Honestly he just needs to get gutted in the jungle. He's a great mid laner (yet no one plays him) and he's toxic in the jungle due to his blistering fast clear speed and uninteractive playstyle where he just farms to win and you have very little input thanks to his godly clear speed.
Lee sin: Has everything you need as a jungler. Needless to say, this is toxic as he whenever he's changed the change affects him significantly. He should lose SOMETHING in his kit to make him fair, whether that be his shield on allies, attack speed from passive or even the lifesteal+spell vamp on W, something needs to go.
Xin Zhao: Deals too much damage early-mid and has very little counterplay besides "run away before he gets near you".
Top lane:
Riven: A one trick based champion that breaks almost every AD item/rune/aspect and lacks any real counterplay once a player nails just a few combos and possible variations of said combos. She breaks Conqueror, Aftershock, crit, Death's Dance, Lethality, you name it, she breaks it. Oh, and for those of you curious, she more than breaks Spear of Shojin, that item alone makes her extremely obnoxious.
Aatrox: His rework flopped balance wise. We've gone full circle, he was awful initially, then he got buffed and he was broken, then he got nerfed, then he got reworked+buffed and his godly again, and let me guess; when he gets nerfed again he'll be awful again? Sorry, but that's toxic to a T. At the very least his rework gave him a lil more counterplay, so I guess that's nice, but now they need to drastically fix his numbers, which will result in him being awful again.
Jax: Spear of Shojin, nuff said. Next!
Nasus: His Q did not need that buff, and his ult lowering the cooldown makes him a living nightmare. Ask any top lane main, post 6, Nasus is not fun to fight.
Tryndamere: He right clicks you and presses R whenever you think you're about to win. I don't even have to say anymore, this champ just desperately needs a rework to help fix his lack of counterplay and linear gameplay.
Tahm Kench: The flavour of the month toxic top lane champ. Get him out of top lane and back to support...PLEASE!
Kennen: Ranged top laner with extremely good CC. Honestly that's all I need to say.
ADC:
Vayne: All of her ult buffs make it so that without ult she has counterplay, but the moment she hits that R button she loses ALL of it besides randomly CCing her during ult. Please revert her ult buffs, thank you.
Ezreal: His Q being a basic attack AND an ability means that he just breaks most if not all new "things" which Riot brings out. He broke Iceborn, Runeglaive, Klepto, Spirit of the Elder Lizard....the list goes on. That and he's extremely safe and good at all stages of the game. Currently he's run as a hybrid ADC, and his burst is insane at 3-4 items, like 100% to 25% levels of stupid (one W->Q).
Kai'sa: Hybrid damage dealing champ with a really good shield, poke damage, great all-in damage, great trade potential, invisibility and she's good at all stages of the game. Needless to say, this all makes her toxic, whoever decided to release this abomination needs to really think before they act next time they design a champion.
Kalista: I'll beat the dead horse here, she can never be balanced. This champion fundamentally breaks the game whenever she's good and is next to unplayable whenever she's nerfed.
Draven: Once ahead there's little to no counterplay if he even has half a brain. That alone makes him toxic.
Support: Note: I realise mage supports are extremely toxic, but I have not mentioned any of them simply due to the fact that having a mage as a support as a concept alone is toxic.
Janna: She has a shield, great poke, an amazing disengage ult, a knockup AND her E just got buffed. A very boring, uninteractive and toxic champ.
Pyke: Ok, so here's the thing right, his base kit isn't entirely broken, it's his passive that breaks him and makes him toxic. The fact that if you don't burst him from 100-0 and he heals almost all of the damage if you don't is silly. Rework his passive into something a little less....tank based.
Yuumi: I don't know why anyone thought a champion of this nature was fair, but hey, here we are now. She's a support that possesses EVERYTHING an enchanter could want, including her being able to not be targeted by anyone if she so chooses to get inside another ally champ. Anyone who thinks this champion isn't broken and toxic must have Yuumis that don't have functioning brain or even fingers.
Braum: A staple pick in competitive and really strong in solo queue. This champion is both a passive support and an amazing aggro support, while being a tank to back that up. He wouldn't be toxic, but his passive alone makes it so that he is.
Take all of this with a grain of salt if you want, I just wanted to put this all out there. Some of this is purely my opinion of a champ's aspects. Honestly, I just wanted to cover the mid and top lane champs, the rest are just bonuses.
Mid lane
Any role
Hello, did someone order CC? Well I have 3 orders of it.