This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Grazle wants you to prove yourself by killing 6 Deadwood Warriors, 6 Deadwood Pathfinders, and 6 Deadwood Gardeners. Return to him in southern Felwood near the Emerald Sanctuary when you are done.
The Timbermaw are the only furbolg tribe to escape the corruption. However, many other races kill furbolg blindly now, without bothering to see if they are friend or foe. For this reason, the Timbermaw furbolg trust very few.
Are you interested in proving yourself? Drive back the corrupted Deadwood tribe of Felwood and we may one day consider you an ally. You'll find the first Deadwood tribe - warriors, pathfinders and gardeners - to my west.