Speak to Queen Caleuh at -151, -685, -707 near the Sanctuary of Tears to begin this quest.
Save 3 sifaye budlings from corruption. To do this you must fight it to no health and then it will follow you back to the queen. You'll need to do one budling at a time. If this happens to you, turn off their protect and assist.
On Test, mercenaries getting the killing blow caused this step to not update.