Neltharion's Lair: Essence of Tenacity - Quest Giver Does Not Show Up

The Essence quests for Druids are obtained in the Dreamway by going to the appropriate stone and using the appropriate ability. If you abandon this quest and need to pick it up again, you'll need to go back to the stone in the Dreamway and transform to bear shape. The quest Essence of Tenacity should be available then.