Caitlyn Runes explained
There's one set of runes for Caitlyn on patch 14.22 that is the clear favorite for LoL players and pros alike. The best Caitlyn rune paths on the position 
Adc are 
Precision as the primary path and 
Sorcery as the secondary path with a pick rate of 81%. Besides picking runes on Caitlyn you should learn how to play Caitlyn and if you are interested in pro matches take a look on how a pro builds Caitlyn. If you want to discuss 
Caitlyn then you should visit the champion subreddit.
Caitlyn runes from primary path
Precision improves attack and sustained damage on Caitlyn 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 Caitlyn. This keystone rune gives Caitlyn a great head start in team fights and allows to put out more damage in that time window. Other primary runes on Caitlyn are 
Presence of Mind, 
Legend: Bloodline and 
Cut Down.
Presence of Mind helps Caitlyn 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.
Caitlyn runes from secondary path
When it comes to your secondary path, most Caitlyn players prefer to go with Sorcery. Sorcery empoweres abilities of Caitlyn and increases the available champion resources. On the Sorcery path, the best runes for Caitlyn are 
Gathering Storm and 
Absolute Focus.
Gathering Storm increases your late game power. Absolute Focus grants additional damage while Caitlyn is alomst full health.
FAQ for Caitlyn Runes
Which is the best keystone rune on Caitlyn?
The best keystone rune on Caitlyn is Lethal Tempo. This Caitlyn runes setup is then referred as Caitlyn Lethal Tempo.
What runes does Caitlyn use?
Runes from the paths Precision and Sorcery are the most used runes on Caitlyn. For the exact pick rates of Caitlyn runes used, you have to study the rune distribution presented.