Enter Jaedenar and slay 4 Jaedenar Hounds, 4 Jaedenar Guardsmen, 6 Jaedenar Adepts, and 6 Jaedenar Cultists before returning to Greta Mosshoof in Felwood.
If I am to trust you in this matter, you will first have to prove yourself.
I must know that you are an enemy of the Shadow Council--the ones responsible for many evils here and abroad.
Travel deeper into Felwood. To the west you will see a path leading to Jaedenar. It is there that the Council plots with the Burning Legion.
Enter the depths of one of the corrupted Barrow Dens they inhabit and slay their kind. Return to me after you've done this. Then I will know you truly seek to help us.