Jax Runes explained
There's one set of runes for Jax on patch
11.20
that is the clear favorite for LoL players and pros alike. The best Jax Runes on the position 
Top are Precision as the primary path and
Inspiration as the secondary path with a pick rate of 90%. Besides runes you should take a look on Jax Build and if you are interested in pro matches take a look at Jax Probuilds. If you want to discuss
Jax then you should visit the champion subreddit.
Primary path on Jax
Precision improves attack and sustained damage on Jax 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
Jax. This keystone rune provides additional power in the later stages of a game. As soon as
Conqueror is fully charged, Jax deals additional damage and gains life steal. This is usually followed up by taking
Triumph,
Legend: Alacrity and
Last Stand.
Triumph restores on Jax a part of missing health and award bonus gold, if a champion is killed.
Legend: Alacrity grants additional attack speed to Jax. With
Last Stand you deal more damage while you are at low health.
Secondary path on Jax
When it comes to your secondary path, most
Jax players prefer to go with
Inspiration.
Inspiration opens creative opportunities on Jax troughout the match. On the
Inspiration path, the best runes for Jax are
Time Warp Tonic and
Biscuit Delivery.
Time Warp Tonic gives you additional sustain by boosting your
Biscuit Delivery is a great rune for laning as it gives additional health and mana, which can help in more aggressive lanes.
FAQ for Jax Runes
Which is the best keystone rune on Jax?
The best keystone rune on Jax is
Conqueror.