Sorcery + Precision as Skarner Runes
This setup uses Phase Rush on Skarner as the keystone rune. Phase Rush, upon landing three separate attacks or abilities with Skarner onto an enemy champion, grants a burst of movement speed to you. This is a great way of weaving in and out of danger during full scale fights, as well as giving your opponent less of an opportunity to trade damage back onto you in smaller skirmishes.
As secondary Pros prefer the Precision tree, taking Triumph and Legend: Alacrity. These runes are great at helping Skarner scale a bit better and allowing to gain some health after taking down an enemy champion.