Vi Runes explained
There's one set of runes for Vi on patch
11.8
that is the clear favorite for LoL players and pros alike. The best Vi Runes on the position 
Jungle are Precision as the primary path and
Domination as the secondary path with a pick rate of 43%. Besides runes you should take a look on Vi Build and if you are interested in pro matches take a look at Vi Probuilds. If you want to discuss
Vi then you should visit the champion subreddit.
Primary path on Vi
Precision improves attack and sustained damage on Vi 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
Vi. This keystone rune provides additional power in the later stages of a game. As soon as
Conqueror is fully charged, Vi deals additional damage and gains life steal. This is usually followed up by taking
Triumph,
Legend: Alacrity and
Coup de Grace.
Triumph restores on Vi a part of missing health and award bonus gold, if a champion is killed.
Legend: Alacrity grants additional attack speed to Vi. Vi deals with
Coup de Grace more damage to targets with low health.
Secondary path on Vi
When it comes to your secondary path, most
Vi players prefer to go with
Domination.
Domination improves burst damage and assassination tools on Vi. On the
Domination path, the best runes for Vi 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 Vi 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.