Tzik'nith is a Lamia who may be found in the Hollow City in Coldharbour. She will only be found in the city if you choose her side over that of the Shadow Walker Wood Elves in the quest Into the Woods.
"We shall help you enter the tower. But first, you must help us against these foul Wood Elves. Do not listen to their lies! They murder our children! For no reason! Please, you must help me save the little ones! - Tzik'nith during Into the Woods
The final assault to end the Planemeld is at hand. We need to fight our way through Molag Bal's defenses and reach the portal to the planar vortex. Only then can we end this threat and save our world.