This is my basic guide for master yi for low elo i used to climb through silver elo. Some people need a bit of help with what to build and what to take so ill tell you guys what i take and prefer. I personally believe this is the best way to play him right now but there are definitely other variations and combinations that are good with him.

I love attack speed, i think that is the best bet for early clear and the seals give a lot of health late game, armor could be substituted instead though, if you prefer.

Self explanatory, I got them from Pants are Dragon and I like them a lot, think they are the best bet.

Starting item are pretty self explanatory
Skirmishers are the best for auto attacking
Devour is op on yi, but with the upcoming patches idk
Same with devour, Rageblade is good and i love it but idk how well it will stand
Gage is just one of the overal best items for ad, with tank
Personally like dead mans and spirit visage they give good stats for tankyness
Bork and Hex, hex just in case they have a lot ap it isn't a bad item and bork if you are super ahead is good.

Q is his main key, w second cause it is really good in case you get invaded. But max E second and then W, with R maxed at lvl 16.

Flash and smite, nothing else maybe TP but flash is just overall the best.

He gets banned alot but when you do get him he is really good for low elo.
HOW TO GANK, WHEN TO GANK AND WHEN TO FARM COMING SOON

I start blue side clear all camps, maybe get the crab especially if it is against a kindred. I always try to take those against kindred.