League of Legends has one of the most toxic game environments in gaming today. Frankly a lot of that is created through sheer frustration and a feeling of helplessness created by certain factors inside the game. While Riot tries to keep things balanced, sometimes important things just slip through the cracks. In trying to balance the ridiculously overpowered AP Master Yi, they instead recreated him into another monstrous form. 

At present, Master Yi is one of the most unbalanced, frustrating and overpowered champions in the game. He is the only champion who has a low-cooldown skill that makes him invisible, untargetable, invulnerable AND deals moderate to high damage. He has a self-heal that gives high damage resistance. He has a skill whose passive buffs his damage or gives him true damage per hit, which shreds even the tankiest champions with his high attack speed. And his low-cooldown ultimate makes him incredibly fast, gives a HUGE attack speed steroid, makes him invulnerable to slows, gets a longer duration for every kill, and passively gives his skills a 70% cooldown reset per kill OR assist, letting him spam his damage skills to remain untargetable for a long portion of any teamfight. To put it lightly, this kit is overloaded. High damage, high sustain, high mobility, semi-immunity to CC, no counterplay, true damage... it's just too much.

Some claim that there's no problem with Yi because at high levels of gameplay his abilities aren't as big a problem, which may or may not be true. What IS true is that over 50% of the entire game's population are below the middle level of skill, which means for the majority of League gamers, that arguement means nothing at all. And not everyone has the time to devote hours and hours of practice a day to change that.

I'm petitioning Riot to rework this champion because the levels of toxicity I've seen come into games solely because of this champion is just too much. I'm hoping that with enough petition signers we can convince Riot to take another look at this problem champion.

I'm sure that part of why this hasn't been addressed yet are difficulties in balancing him, how to keep him relevant without being overpowered. This could be done in any number of ways. Strip the damage resist from his self-heal. Remove his resets to make him less overwhelming and hard to even attack in teamfights. Remove his slow-invulnerability so using his ultimate isn't a nearly guaranteed kill on any non-tank champion and gives people at least a chance to get away. Increase the cooldown on his alpha strike skill, or lower the number of targets it auto-hits. You could even turn alpha strike into a skillshot that makes him dash towards a target before it does its invulnerability/dmg so he could be dodged. 

In summary, this champion is broken and leaving it untended is leading to a more toxic game environment. Please, Riot, take the time to take steps towards fixing this situation. We appreciate your time and attention to this problematic champion.