Jayce Runes explained
There's one set of runes for Jayce on patch 14.12 that is the clear favorite for LoL players and pros alike. The best Jayce rune paths on the position 
Top are 
Precision as the primary path and 
Inspiration as the secondary path with a pick rate of 46%. Besides picking runes on Jayce you should learn how to play Jayce and if you are interested in pro matches take a look on how a pro builds Jayce. If you want to discuss 
Jayce then you should visit the champion subreddit.
Jayce runes from primary path
Precision improves attack and sustained damage on Jayce 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 Jayce. This keystone rune provides additional power in the later stages of a game. As soon as Conqueror is fully charged, Jayce deals additional damage and gains life steal. Other primary runes on Jayce are 
Presence of Mind, 
Legend: Alacrity and 
Last Stand.
Presence of Mind helps Jayce with the mana problems by restoring missing mana, if a champion is killed. Legend: Alacrity grants additional attack speed to Jayce. With Last Stand you deal more damage while you are at low health.
Jayce runes from secondary path
When it comes to your secondary path, most Jayce players prefer to go with Inspiration. Inspiration opens creative opportunities on Jayce troughout the match. On the Inspiration path, the best runes for Jayce are 
Biscuit Delivery and 
Magical Footwear.
Biscuit Delivery is a great rune for laning as it gives additional health and mana, which can help in more aggressive lanes. Magical Footwear allows Jayce to focus on those essential core items without the need to spend the additional 300 gold on boots.
FAQ for Jayce Runes
Which is the best keystone rune on Jayce?
The best keystone rune on Jayce is Conqueror. This Jayce runes setup is then referred as Jayce Conqueror.
What runes does Jayce use?
Runes from the paths Precision and Inspiration are the most used runes on Jayce. For the exact pick rates of Jayce runes used, you have to study the rune distribution presented.