Seraphine Runes explained
There's one set of runes for Seraphine on patch
11.8
that is the clear favorite for LoL players and pros alike. The best Seraphine Runes on the position 
Support are Resolve as the primary path and
Inspiration as the secondary path with a pick rate of 94%. Besides runes you should take a look on Seraphine Build and if you are interested in pro matches take a look at Seraphine Probuilds. If you want to discuss
Seraphine then you should visit the champion subreddit.
Primary path on Seraphine
Resolve empowers the survivability of Seraphine and increases the tankiness. Most of high elo players – and our LoL pros in the the major regions – have agreed that
Guardian is the best keystone rune to run on
Seraphine. This keystone rune grants a shield to your teammate and towards your own, as soon as one of you gets damage by an enemy champion. This is usually followed up by taking
Shield Bash,
Bone Plating and
Revitalize.
Shield Bash powers up your tankiness and empowers your next basic attack while you have a shield.
Bone Plating make Seraphine overall tankier, by decreasing the amount of poke damage in the early game.
Revitalize inceases heals and shields you distribute or receive.
Secondary path on Seraphine
When it comes to your secondary path, most
Seraphine players prefer to go with
Inspiration.
Inspiration opens creative opportunities on Seraphine troughout the match. On the
Inspiration path, the best runes for Seraphine are
Biscuit Delivery and
Cosmic Insight.
Biscuit Delivery is a great rune for laning as it gives additional health and mana, which can help in more aggressive lanes.
Cosmic Insight grants summoner spell and item haste.