This quest is part 1 of 7 for the Fabled version of the Fury-only Epic Weapon, Wrath of Nature.
Go to 192, -44, 169 in Darklight Wood. You'll be offered the quest when you come upon a mutilated deer carcass.
Head to the Wanderlust Fair in Darklight Wood and talk to everyone, especially Torbus Finlow. He tells you to go to the shadow oak. The actual quest starter is the mutilated deer at 191.37,-43.61,167.14