In the sidequest "Rocky" you help the thief Laus in the Thieves' Passage to get a Gornak head.

Laus tells you that Gornak heads are valuable items on the black market and asks you to kill a Gornak and bring the head back to him.

Go to the Blackwhisper Cave where Gornak's roam. Kill one and then go back to Laus.

Talk to him again and receive a reward of 2 Strength auras.