Darkrune

Source
This item is a quest reward from Banish the Demons.

You can also receive a Darkrune from Kronk's Grab Bag, a quest reward from Banish More Demons.

Darkrune as a quest objective
This item is an objective for the following quests:
 * Yous Have Da Darkrune?
 * A Crystalforged Darkrune