Kassadin Runes explained
There's one set of runes for Kassadin on patch 15.2 that is the clear favorite for LoL players and pros alike. The best Kassadin rune paths on the position 
Mid are 
Sorcery as the primary path and 
Domination as the secondary path with a pick rate of 34%. Besides picking runes on Kassadin you should learn how to play Kassadin and if you are interested in pro matches take a look on how a pro builds Kassadin. If you want to discuss 
Kassadin then you should visit the champion subreddit.
Kassadin runes from primary path
Sorcery empoweres abilities of Kassadin 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 Kassadin. This keystone rune adds more damage to your abilities and increases your power in the laning phase. Other primary runes on Kassadin are Axiom Arcanist, Absolute Focus and Gathering Storm.
Axiom Arcanist grants you a shield, as soon as Kassadin gets hurt by alot of magic damage. This rune will help you alot to survive against ability power champions with a lot of burst damage. Absolute Focus grants additional damage while Kassadin is alomst full health. Gathering Storm increases your late game power.
Kassadin runes from secondary path
When it comes to your secondary path, most Kassadin players prefer to go with Domination. Domination improves burst damage and assassination tools on Kassadin. On the Domination path, the best runes for Kassadin are 
Sudden Impact and 
Ultimate Hunter.
Sudden Impact increases your damage after dashing or being invisible. This is due to how easy it is to activate on Kassadin with the amount of ways he has to dash, jump or going invisible. The additional lethality helps to take down the priority targets that much easier. Ultimate Hunter scales up Kassadin ultimate haste on every unique champion takedown.
FAQ for Kassadin Runes
Which is the best keystone rune on Kassadin?
The best keystone rune on Kassadin is Arcane Comet. This Kassadin runes setup is then referred as Kassadin Arcane Comet.
What runes does Kassadin use?
Runes from the paths Sorcery and Domination are the most used runes on Kassadin. For the exact pick rates of Kassadin runes used, you have to study the rune distribution presented.