This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Kill 6 Bristleback Water Seekers, 12 Bristleback Thornweavers and 12 Bristleback Geomancers and return to Mangletooth at Camp Taurajo in the Barrens.
You must strike my enemies. <snort> You must help Mangletooth and the Razormane by weakening the Bristlebacks. Both tribes are very spiritual--tied to the earth and its power. <snort> It gives us strength in all things... especially war.
If you want to find out who really causes Thork <snort> and the Horde such anguish, then help Mangletooth! You attack the spiritual leaders of the Bristlebacks to the north; weaken them so the Razormanes can defeat them and rule the Barrens.