Zilean Runes explained
There's one set of runes for Zilean on patch 15.4 that is the clear favorite for LoL players and pros alike. The best Zilean rune paths on the position 
Support are 
Resolve as the primary path and 
Sorcery as the secondary path with a pick rate of 67%. Besides picking runes on Zilean you should learn how to play Zilean and if you are interested in pro matches take a look on how a pro builds Zilean. If you want to discuss 
Zilean then you should visit the champion subreddit.
Zilean runes from primary path
Resolve empowers the survivability of Zilean 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 Zilean. This keystone rune gives Zilean alot of sustain and helps to force your opposing champion out of the lane. Other primary runes on Zilean are Font of Life, Second Wind and Unflinching.
Font of Life provides your teammates with more sustain by healing them whenever they attack a champion whose movement you've recently impaired. Second Wind powers up your sustainablity in lane by healing after taking damage from an enemy champion. Unflinching inceases Zilean tenacity based on your missing health.
Zilean runes from secondary path
When it comes to your secondary path, most Zilean players prefer to go with Sorcery. Sorcery empoweres abilities of Zilean and increases the available champion resources. On the Sorcery path, the best runes for Zilean are 
Manaflow Band and 
Celerity.
This is usually followed up by taking Manaflow Band for additional mana and mana regenaration. Celerity boosts all movement speed bonuses to Zilean.
FAQ for Zilean Runes
Which is the best keystone rune on Zilean?
The best keystone rune on Zilean is Grasp of the Undying. This Zilean runes setup is then referred as Zilean Grasp of the Undying.
What runes does Zilean use?
Runes from the paths Resolve and Sorcery are the most used runes on Zilean. For the exact pick rates of Zilean runes used, you have to study the rune distribution presented.