Light or Dark magic.

I agree with Dracon Mallasa! When playing as Dwarves, I try to get that rune, especially when playing against Elves or Haven, because they often focus on Light magic. If your hero has developed Pyrokinetics, take this rune (I don't remember the name, it's something complicated) and attack an enemy unit that is under the effect of a spell like "Wrath" or something similar. :):)