Lucian Runes explained
There's one set of runes for Lucian on patch 14.9 that is the clear favorite for LoL players and pros alike. The best Lucian rune paths on the position 
Adc are 
Precision as the primary path and 
Inspiration as the secondary path with a pick rate of 50%. Besides picking runes on Lucian you should learn how to play Lucian and if you are interested in pro matches take a look on how a pro builds Lucian. If you want to discuss 
Lucian then you should visit the champion subreddit.
Lucian runes from primary path
Precision improves attack and sustained damage on Lucian troughout the match. Most of high elo players – and our LoL pros in the the major regions – have agreed that Press the Attack is the best keystone rune to run on Lucian. Lucian has a very easy time activating this rune with basic attacks which synergises well with Press the Attack’s damage increase once activated. Other primary runes on Lucian are Presence of Mind, Legend: Bloodline and Coup de Grace.
Presence of Mind helps Lucian with the mana problems by restoring missing mana, if a champion is killed. Legend: Bloodline gives life steal, which aids in winning damage trades and fights in the later stages of the match. Lucian deals with Coup de Grace more damage to targets with low health.
Lucian runes from secondary path
When it comes to your secondary path, most Lucian players prefer to go with Inspiration. Inspiration opens creative opportunities on Lucian troughout the match. On the Inspiration path, the best runes for Lucian 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 Lucian to focus on those essential core items without the need to spend the additional 300 gold on boots.
FAQ for Lucian Runes
Which is the best keystone rune on Lucian?
The best keystone rune on Lucian is Press the Attack. This Lucian runes setup is then referred as Lucian Press the Attack.
What runes does Lucian use?
Runes from the paths Precision and Inspiration are the most used runes on Lucian. For the exact pick rates of Lucian runes used, you have to study the rune distribution presented.