Master Yi Runes explained
There's one set of runes for Master Yi on patch
11.8
that is the clear favorite for LoL players and pros alike. The best Master Yi Runes on the position 
Jungle are Precision as the primary path and
Domination as the secondary path with a pick rate of 25%. Besides runes you should take a look on Master Yi Build and if you are interested in pro matches take a look at Master Yi Probuilds. If you want to discuss
Master Yi then you should visit the champion subreddit.
Primary path on Master Yi
Precision improves attack and sustained damage on Master Yi troughout the match. Most of high elo players – and our LoL pros in the the major regions – have agreed that
Conqueror is the best keystone rune to run on
Master Yi. This keystone rune provides additional power in the later stages of a game. As soon as
Conqueror is fully charged, Master Yi deals additional damage and gains life steal. This is usually followed up by taking
Triumph,
Legend: Alacrity and
Coup de Grace.
Triumph restores on Master Yi a part of missing health and award bonus gold, if a champion is killed.
Legend: Alacrity grants additional attack speed to Master Yi. Master Yi deals with
Coup de Grace more damage to targets with low health.
Secondary path on Master Yi
When it comes to your secondary path, most
Master Yi players prefer to go with
Domination.
Domination improves burst damage and assassination tools on Master Yi. On the
Domination path, the best runes for MasterYi are
Ravenous Hunter and
Sudden Impact.
Ravenous Hunter is the final rune of the
Domination path. This rune gives some survivability during short fights and damage trades during the laning phase. The additional health is nothing to scoff at and can mean the difference between winning or losing a battle.
Sudden Impact increases your damage after dashing or being invisible. This is due to how easy it is to activate on Master Yi with the amount of ways he has to dash, jump or going invisible. The additional lethality helps to take down the priority targets that much easier.