Collect a Glowing Soul Gem and return it to Delgren the Purifier at Maestra's Post.
Balthule's letter is dire. This Cult of the Dark Strand is a thorn in my side that must be removed. I have been dealing with some of the Dark Strand scum northeast of here at Ordil'Aran. One of their number possesses a soul gem that I believe holds the secret to the cult's power.
Bring it to me, and I will be able to decipher the secrets held within.
Have you acquired that soul gem?
Hmm, some dark magic enchants this soulstone. Let's see what's trapped inside, shall we?
Upon completion of this quest you will gain: