Personally dont like Yammu's. Sark's fevor is good though for yi. If your fighting a TON of mages, you may want a WE, takes 42 mana/hit unless its allready draind. Very affective especially with yi's 7th hit. Infinity edge, personally not a huge fan of it unless really late game against tanks... if they r squishy then dont really need to bother with IE.
Ill share with you how i play Master Yi.
I start out with rejuvination beads, grab 3 health potions and 3 mana potions. Early game for a few lvls you want to harras them. Get wuju style to start out with but then build 2 times into your alpha strike, then build into your W, some things people don't realize about master yi's W is that you can actually TANK THINGS AT LOWER LVL WITH IT! If, for example, you get trapped by a morgana's paralyze and she goes to use her sludge shit on ya, pop your W you heal her dmg and you take less dmg aswell and if your team-mate is near ya, well, go get'em tiger.
You can actually solo mid easly but i usually don't do it against ranged champs but i have done it against close-combat dps champs. Another thing is that attack speed+life steal and some more damage is all you really need for him. May need merc treads instead of your own preferd boots just incase (like this week) your up against stunners or taunters... like annie, ashe, rammus and others. I allways get Last Whisper, armor pen is AMAZING
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
that with sark's fevor, is a tank destroyer. If however your up against a good tank, like... rammus! only attack him when hes out of defence curl, he is standing on all fours when in defence curl and if he has buffs they hover around his ass not his waist
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
. When he gets outa defence curl that is your chance to strike, if you do have black clevar then that is your big ticket item because it reduces his armor very fast + your double hit will assist you aswell. I like bloodthirsters on Yi just because the lifesteal and damage will stack/champ kill... and more dmg and lifesteal is great?
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
You may, or may not get a divine sword, personally love that item for kennen though
![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
(every 4th attack does bonus magic dmg of 100 dmg, then your 5th attack does bonus magic damage and adds a star... great combo with kennen!)