There is one last moonwell that I would like you to visit. It is directly south of here, on the shores of the Pools of Arlithrien. Be wary as you seek out the well, and keep your weapons close at hand. I sense a growing corruption from the boughs of southern Teldrassil.
When you have the water, I want you to bring it to a familiar face that you'll see at the pools. She wishes to battle the corruption, and has asked for you personally.
Indeed, I have spoken to Corithras on my way here, and he has gifted me with the waters you have been gathering. They may well prove useful sooner than we'd imagined.
Strangely, the growing corruption we've felt is actually a good sign. Teldrassil has been burdened with this taint for a long time, and thanks to the blessing of the dragon aspects, only now is it coming to the surface in a form that we might strike against.