Amumu Runes explained
There's one set of runes for Amumu on patch 13.24 that is the clear favorite for LoL players and pros alike. The best Amumu rune paths on the position 
Support are 
Inspiration as the primary path and 
Domination as the secondary path with a pick rate of 38%. Besides picking runes on Amumu you should learn how to play Amumu and if you are interested in pro matches take a look on how a pro builds Amumu. If you want to discuss 
Amumu then you should visit the champion subreddit.
Amumu runes from primary path
Inspiration opens creative opportunities on Amumu troughout the match. Most of high elo players – and our LoL pros in the the major regions – have agreed that Glacial Augment is the best keystone rune to run on Amumu. This keystone rune slows enemy champion on your first basic attack. This slow can by followed up by a skill shot of Amumu to force the opponent in a dangerous situation. Other primary runes on Amumu are Hextech Flashtraption, Minion Dematerializer and Cosmic Insight.
Having an extra way to decrease the distance with the Hextech Flashtraption will make an engage much easier to pull off. Minion Dematerializer will help you to control the position of the minion wave. Cosmic Insight grants summoner spell and item haste.
Amumu runes from secondary path
When it comes to your secondary path, most Amumu players prefer to go with Domination. Domination improves burst damage and assassination tools on Amumu. On the Domination path, the best runes for Amumu are 
Ultimate Hunter and 
Cheap Shot.
Ultimate Hunter scales up Amumu ultimate haste on every unique champion takedown. Cheap Shot makes you deal more damage to enemies with impaired movement, which has great synergy with the setup of Amumu.
FAQ for Amumu Runes
Which is the best keystone rune on Amumu?
The best keystone rune on Amumu is Glacial Augment. This Amumu runes setup is then referred as Amumu Glacial Augment.
What runes does Amumu use?
Runes from the paths Inspiration and Domination are the most used runes on Amumu. For the exact pick rates of Amumu runes used, you have to study the rune distribution presented.