This will be my official first builds that arent just for kicks. The first 2 pages will be Yi who i find to be a very basic AD char but one of my favs XP.

1st page basic AD hero make up that is meant for output but nothing to special in my opinion and very squishy late game. Sure your a huge threat but not if you get stunned a few times...
And over all just could be made differently as i feel.

2nd The Master Yi: Start with crit gloves knowing your masteries give you 12% + 8% from gloves + 6% off your runes makes for a starting 26% to crit which is really nice. XD Work in the 5 gold asap to top off your criting at 32%. Boots, zeal, and scepter so you can stay in lane a bit longer and vsing 1v1 or even 1v2 stands the chance of winning out by a lot. After scepter always get the cloak for cases if your not winning to well you can default into phantom or if your winning out well enough to make infinity blade. Either way you should be making both after one or the other.
Now at this point is where you have to decide on the last 3 items. Keep in mind to try and save your 5 gold item to be sold off last and be replaced with impaler knowing that your stacks in your warmogs and blood are always there for lvling until they are maxed or you die.
Page 2 is probably the best Yi page allowing for plenty crit % and health. The shown skills and items are idealistic in a pwning game. Knowing when to get certain items and skills is very vital. Slowing and mana problems can be solved with buffs and or making mallet along side with zeal.