Zyra Runes explained
There's one set of runes for Zyra on patch
11.19
that is the clear favorite for LoL players and pros alike. The best Zyra Runes on the position 
Support are Sorcery as the primary path and
Domination as the secondary path with a pick rate of 70%. Besides runes you should take a look on Zyra Build and if you are interested in pro matches take a look at Zyra Probuilds. If you want to discuss
Zyra then you should visit the champion subreddit.
Primary path on Zyra
Sorcery empoweres abilities of Zyra and increases the available champion resources. Most of high elo players – and our LoL pros in the the major regions – have agreed that
Arcane Comet is the best keystone rune to run on
Zyra. This keystone rune adds more damage to your abilities and increases your power in the laning phase. This is usually followed up by taking
Manaflow Band,
Transcendence and
Scorch.
This is usually followed up by taking
Manaflow Band for additional mana and mana regenaration.
Transcendence for some more Ability Haste.
Scorch increases your control in the early game.
Secondary path on Zyra
When it comes to your secondary path, most
Zyra players prefer to go with
Domination.
Domination improves burst damage and assassination tools on Zyra. On the
Domination path, the best runes for Zyra are
Taste of Blood and
Relentless Hunter.
Taste of Blood heals Zyra as soon as you damage an opposing champion.
Relentless Hunter increases your movement speed out of combat due to every unique champion takedown.