Master Yi is a fast character that can deliver great amount of damage in short period of time. He is one of the greatest carry/pusher/farmer ingame.
Apart of great dps, huge criticals, great attack speed he has a superb chasing mechanism as well as it can be used as superb escape mechanism.

Pros
+Great damage
+Great attack speed
+Superb chaser
+Great escape mechanism
+Superb pusher/carry/farmer
+Easy to play
+Good harraser

Cons
-Squishy early game
-Vulnerable to disables
-Easy to harrass (Melee)
-Low HP pool
-After using ultimate on a gank that is not working out, he has no way of fleeing from battle.

Double Strike - Master Yi strikes twice every 7th attack.

Alpha Strike - Master Yi leaps across the battlefield with blinding speed, dealing magic damage to multiple units in his path with a chance to deal bonus magic damage to minions.
Master Yi leaps across the battlefield striking up to 4 enemies, dealing 100/150/200/250/300 (+1 per ability power) magic damage to each enemy with a 20/30/40/50/60% chance to deal 400 bonus magic damage to minions.
Cooldown - 18/16/14/12/10 seconds
Cost - 80/90/100/110/120 Mana
Range - 600

Meditate - Master Yi rejuvinates his body by focus of mind, restoring health and increasing his armor and magic resistance for a short time.
Master Yi channels, restoring 140/280/420/560/700 (+1.65 per ability power) health over 5 seconds. While channeling, Master Yi gains 100/150/200/250/300 armor and magic resistance.
Cooldown - 35 seconds
Cost - 70/85/100/115/130 Mana
Range - Self


Wuju Style - Master Yi becomes skilled in the art of Wuju, passively increasing the power of his physical attacks. Activating Wuju Style doubles the passive bonus damage for a short time, but the passive bonus is temporarily removed after the effect wears off.
Passive: Increases physical damage by 15/20/25/30/35.
Active: Master Yi can activate this ability to double its effectiveness for 10 seconds, but this removes the passive bonus until Wuju Style becomes available again.
Cooldown - 25 seconds
Cost - 40 Mana
Range - Self

Highlander - Master Yi moves with unparalleled agility, temporarily increasing Master Yi's movement and attack speeds as well as making him immune to all slowing effects. Additionally, killing a Champion refreshes all of Master Yi's cooldowns.
Increases Master Yi's movement speed by 40% and Attack Speed by 40/60/80%, and he becomes immune to all slowing effects for 6/9/12 seconds. Additionally, killing a champion refreshes all of Master Yi's cooldowns, and scoring an assist reduce the cooldowns by half.
Cooldown - 75 seconds
Cost - 120/120/120 Mana
Range - Self

For some combos with Master Yi, I usually use, Alpha Strike, Wuju Style, then Highlander, it's pretty efficient. Or if you think it fails, then use Highlander when you're trying to flee but usually your mana will be very very low so careful what you choose next cause if you have barely any mana, there is no chance of running away with Highlander.

For summoner spells I usually use,
Exhaust, because I can slow the enemy down and use Flash, I don't really know why I need Flash but OKAY.

Berseker Greaves are for movement speed and attack speed.
Tiamat is for attack damage, HP and MP regen.
Wriggle's Lantern is for life steal, armor and life steal.
Infinity Edge is for massive damaga and massive criticals.
Frozen Mallet is for attack damage and tons of health and slows the enemy with every attack.
Phantom Dancer is for Movement Speed, Criticals, and some attack speed.

Pros
+Great damage
+Great attack speed
+Superb chaser
+Great escape mechanism
+Superb pusher/carry/farmer
+Easy to play
+Good harraser

Cons
-Squishy early game
-Vulnerable to disables
-Easy to harrass (Melee)
-Low HP pool
-After using ultimate on a gank that is not working out, he has no way of fleeing from battle




ouble Strike - Master Yi strikes twice every 7th attack.

Alpha Strike - Master Yi leaps across the battlefield with blinding speed, dealing magic damage to multiple units in his path with a chance to deal bonus magic damage to minions.
Master Yi leaps across the battlefield striking up to 4 enemies, dealing 100/150/200/250/300 (+1 per ability power) magic damage to each enemy with a 20/30/40/50/60% chance to deal 400 bonus magic damage to minions.
Cooldown - 18/16/14/12/10 seconds
Cost - 80/90/100/110/120 Mana
Range - 600

Meditate - Master Yi rejuvinates his body by focus of mind, restoring health and increasing his armor and magic resistance for a short time.
Master Yi channels, restoring 140/280/420/560/700 (+1.65 per ability power) health over 5 seconds. While channeling, Master Yi gains 100/150/200/250/300 armor and magic resistance.
Cooldown - 35 seconds
Cost - 70/85/100/115/130 Mana
Range - Self


Wuju Style - Master Yi becomes skilled in the art of Wuju, passively increasing the power of his physical attacks. Activating Wuju Style doubles the passive bonus damage for a short time, but the passive bonus is temporarily removed after the effect wears off.
Passive: Increases physical damage by 15/20/25/30/35.
Active: Master Yi can activate this ability to double its effectiveness for 10 seconds, but this removes the passive bonus until Wuju Style becomes available again.
Cooldown - 25 seconds
Cost - 40 Mana
Range - Self

Highlander - Master Yi moves with unparalleled agility, temporarily increasing Master Yi's movement and attack speeds as well as making him immune to all slowing effects. Additionally, killing a Champion refreshes all of Master Yi's cooldowns.
Increases Master Yi's movement speed by 40% and Attack Speed by 40/60/80%, and he becomes immune to all slowing effects for 6/9/12 seconds. Additionally, killing a champion refreshes all of Master Yi's cooldowns, and scoring an assist reduce the cooldowns by half.
Cooldown - 75 seconds
Cost - 120/120/120 Mana
Range - Self




For some combos with Master Yi, I usually use, Alpha Strike, Wuju Style, then Highlander, it's pretty efficient. Or if you think it fails, then use Highlander when you're trying to flee but usually your mana will be very very low so careful what you choose next cause if you have barely any mana, there is no chance of running away with Highlander.




For summoner spells I usually use,
Exhaust, because I can slow the enemy down and use Flash, I don't really know why I need Flash but OKAY.




Berseker Greaves are for movement speed and attack speed.
Tiamat is for attack damage, HP and MP regen.
Wriggle's Lantern is for life steal, armor and life steal.
Infinity Edge is for massive damaga and massive criticals.
Frozen Mallet is for attack damage and tons of health and slows the enemy with every attack.
Phantom Dancer is for Movement Speed, Criticals, and some attack speed.