Hello!
I main Yi since season1. So my guide can be very helpfull for those who are interested. Here are my Yi guide for every lane. (top/jungle,adc builds and tips i will add later.)
WHY LANE/MID YI? Myth that Yi sucks on lane is mainly generated by poor game understanding and stereothypical thinking. also Cowsep doesnt understand power of mid yi. To play Yi on mid i got inspired by Faker. i used to think that sated devourer is must have item for yi to be good. Just start corruping potion and u wil have no problem on lane. Mid yi is actually better than jungle, since jungle yi can't do early ganks. also midlaner got bigger impact on game. with 20%cdr u can roam like a beast and help literally every single lane. For mid yi i reccomend to go ignite/flash. But u can also run tp instead of ignite.
Yi is very strong and versatile champ in terms what he can do. He can assasinate, he can push, he can shred tanks . so bassically u can do anything except hard crowdcontrol with this champ.
most likely playing yi means - if u arent behind, u are actually ahead. because longer games go, stronger u become. ofc. its better if u are ahead, but i think there is no other champ in league who can do such insane comebacks as yi. if ur adc is more fed and enemies focus him instead of u, u can pick up some kils easily. if u play junge yi, which is tankier version of yi than mid yi, u will be very tanky and deal a lot of dmg at same time. and even as mid yi, u can get items which prevents u from getting bursted down and still deal tons of dmg. so its not so easy to focus yi. also alpha strike to dodge cc is quite painfull for ur enemies.
Yi is falsely considered as one of the easiest champs in lol. where the truth is he is harder than about half of lol champions. he may seem easy, because he is strong, he can't be slowed or well kited, but if u compare yi to champions like ww, malphite, annie, garen, xin, jax - yi takes much more skill to play him on very high level and actually carry hopeless games. why yi is harden then champions i mentioned? mainly because of alpha strike, its not supper hard to dodge skillshots or cc on u, but at the same time it isnt ez as well. also u must have a good prediction power to know when enemy will flash over the wall so u can follow him with alpha strike. and sometimes u also need some luck. but if u see jax for example, he got no need for prediction power same as yi do. as jax mechanically hardest thing is to hotkey trinker and jump on it, whic is by far easier than do something with alpha. also good meditation use isnt that mechanically easy if u need to use properly in some action situation.
GAME KNOWLEDGE AND DECISION MAKING - u need it to play any champion, so i will not talk much about it, but u need a game knowledge and good decision making to win. as yi - no matter jungle or mid, u must find balance between farming, pushing and killing or helping ur team. u shouldnt allways run for kills or allways push. remember even if ur opponent laner roams, u dont need to do it the same allways, cause when he roams u get gold and exp, while he doesnt. ofc its good if u feel or see where he goes and can counter gank, but if he is allready at botlane most likely there is no point to run after him. better push turret.
HOW TO 1V1 - Yi is 1v1 GOD! there is no champion who can 1v1 jungle yi lategame excepet good vayne with landed condemn and ultimate. when u have no place to buy vision ward. mid yi can get rekt by jax if yi doesnt dodge his stun. i think u can't 100% dodge jax stun, so again u wil need prediction power. u can see how quick jax cast his stun on first 1v1 u make and then hope that next time he will do the same. allways meditate while jax is in his e, to reduce his dmg deal to u. yi can get rektby teemo if yi doesnt have qss. - depends how fed jax and teemo are actually. at level 6 u can 1v1 most of champions if u arent behind, so dont be affraid to fight.
so thats bassically it! thnx for reading my guide. feel free vote or comment .