Felling Spites is the kill quest for chapter 4 of the Dwarf WAR story, Keeping the Dogs at Bay. The kill collector for this quest is Barin Grimbeard, who can be found at Dragonbone Pass, in the zone of Mount Bloodhorn.
On Completion Edit
I'm paying for every Snotwood Spite killed. I'll keep paying until the forest's empty or my thirst for vengeance is slaked.