Nocturne Runes explained
There's one set of runes for Nocturne on patch
11.20
that is the clear favorite for LoL players and pros alike. The best Nocturne Runes on the position 
Jungle are Precision as the primary path and
Domination as the secondary path with a pick rate of 97%. Besides runes you should take a look on Nocturne Build and if you are interested in pro matches take a look at Nocturne Probuilds. If you want to discuss
Nocturne then you should visit the champion subreddit.
Primary path on Nocturne
Precision improves attack and sustained damage on Nocturne troughout the match. Most of high elo players – and our LoL pros in the the major regions – have agreed that
Lethal Tempo is the best keystone rune to run on
Nocturne. This keystone rune gives Nocturne a great head start in team fights and allows to put out more damage in that time window. This is usually followed up by taking
Triumph,
Legend: Alacrity and
Coup de Grace.
Triumph restores on Nocturne a part of missing health and award bonus gold, if a champion is killed.
Legend: Alacrity grants additional attack speed to Nocturne. Nocturne deals with
Coup de Grace more damage to targets with low health.
Secondary path on Nocturne
When it comes to your secondary path, most
Nocturne players prefer to go with
Domination.
Domination improves burst damage and assassination tools on Nocturne. On the
Domination path, the best runes for Nocturne are
Ultimate Hunter and
Eyeball Collection.
Ultimate Hunter scales up Nocturne ultimate haste on every unique champion takedown.
Eyeball Collection is next up. This grants the user additional damage with every killing they score.
FAQ for Nocturne Runes
Which is the best keystone rune on Nocturne?
The best keystone rune on Nocturne is
Lethal Tempo.