Lucian Runes explained
There's one set of runes for Lucian on patch
11.19
that is the clear favorite for LoL players and pros alike. The best Lucian Runes on the position 
Adc are Precision as the primary path and
Inspiration as the secondary path with a pick rate of 66%. Besides runes you should take a look on Lucian Build and if you are interested in pro matches take a look at Lucian Probuilds. If you want to discuss
Lucian then you should visit the champion subreddit.
Primary path on Lucian
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. This is usually followed up by taking
Presence of Mind,
Legend: Bloodline and
Cut Down.
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. If the enemy team consists of multiple tanks, then the rune
Cut Down is the best choice.
Secondary path on Lucian
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 players to focus on those essential core items without the need to spend the additional 300 gold on boots.