Azir Runes explained
There's one set of runes for Azir on patch 14.10 that is the clear favorite for LoL players and pros alike. The best Azir rune paths on the position 
Mid are 
Resolve as the primary path and 
Precision as the secondary path with a pick rate of 30%. Besides picking runes on Azir you should learn how to play Azir and if you are interested in pro matches take a look on how a pro builds Azir. If you want to discuss 
Azir then you should visit the champion subreddit.
Azir runes from primary path
Resolve empowers the survivability of Azir and increases the tankiness. Most of high elo players – and our LoL pros in the the major regions – have agreed that Grasp of the Undying is the best keystone rune to run on Azir. This keystone rune gives Azir alot of sustain and helps to force your opposing champion out of the lane. Other primary runes on Azir are Demolish, Bone Plating and Overgrowth.
Demolish increases your pressure on the enemy turrets. This rune will help you to punish bad roams or backtimings of your lane opponent. Bone Plating make Azir overall tankier, by decreasing the amount of poke damage in the early game. Overgrowth increases your maximum amount of health.
Azir runes from secondary path
When it comes to your secondary path, most Azir players prefer to go with Precision. Precision improves attack and sustained damage on Azir troughout the match. On the Precision path, the best runes for Azir are 
Presence of Mind and 
Legend: Alacrity.
Presence of Mind helps Azir with the mana problems by restoring missing mana, if a champion is killed. Legend: Alacrity grants additional attack speed to Azir.
FAQ for Azir Runes
Which is the best keystone rune on Azir?
The best keystone rune on Azir is Grasp of the Undying. This Azir runes setup is then referred as Azir Grasp of the Undying.
What runes does Azir use?
Runes from the paths Resolve and Precision are the most used runes on Azir. For the exact pick rates of Azir runes used, you have to study the rune distribution presented.