Keeper of the ancient art of Wuju, Master Yi is a mystical warrior from the isle of Ionia. He descended from one of the few tribes dedicated to the preservation of Wuju, a martial art founded with the principles of absolute spiritual awareness of one's self and one's enemy. When the armies of Noxus invaded Ionia, Master Yi joined in the Ionian defense to fight the craven enemy, bringing his village honor through his unparalleled mastery of the blade. The ensuing battles ravaged the land, but no conflict inflicted as much horror as the day the armies of Noxus closed in on Yi's village. Left undefended, the village became the unfortunate test subject of the latest invention by an up-and-coming chemist, now known as Singed. The remains of the village that Master Yi returned to were so horrific that it remains a festering scar on Ionian history. To this day, no Ionian will ever publicly speak of what occurred.
After the Noxian invasion was contained, Master Yi fell into a deep isolation. For years, he trained morning to night, speaking to no one and refusing offers of consolation by fellow Ionians. The only thing stopping him from madly charging into Noxus battle lines headfirst was his pledge to keep the Wuju style alive. Even though he seethed with impatience, his rage became a tool for sharpening his practice of Wuju, developing stronger and deadlier skills for his eventual vengeance. The only thing that roused him was news of the League's formation, and Noxus's subsequent enrollment in the League. Master Yi now brings his mastery of the blade to the League of Legends with unflinching purpose: to avenge his kinfolk and end the predations of the Noxus once and for all.
"The art of Wuju lives on in Master Yi, and is plunged through the hearts of his foes."
Soraka, The Starchild

Goggles from the InventorEdit
The goggles Master Yi wears are a techmaturgical device that was gifted to the champion by Piltover's own Heimerdinger, the Revered Inventor. Master Yi first used these goggles when defending his homeland from Noxus invaders in the time after the League has just formed and before Ionia had affiliated itself with the League. The goggles are fitted specifically for Master Yi; while someone else may wear them, they won't receive anywhere near the same benefit as he does himself.
The one-of-a-kind goggles, known as the "Seven Lenses of Insight", allow Master Yi to see across a wider range of the spectrum than normal people see. They also give him abilities not dissimilar to that of real world binoculars and telescopes. The goggles are synced to Yi's own magical resonance, allowing him to adjust settings without the use of his hands. He simply thinks what he needs, and the goggles act accordingly.

Some people start with 5 health potions but i don't .I always start with the Boots Of Speed.
Then i take the attack speed boots. I don't take instant Phantom Dancer. I first take Zeal .Then
i take the Bloodthirster and then i finish the Phantom Dancer .

Pros Cons

-Great burst -Low HP
-Fast speed -Not so great in team fights
-Good farmer

Master Yi is a very good farmer .Whith lv 5 Alpha Strike he kills 4 minions instant.