This quest is not available in game.
Find Deathguard Kel and heal his wounds using Lesser Heal (Rank 2). Afterwards, grant him Power Word: Fortitude and then return to Dark Cleric Beryl in Brill.
Our power comes from darkness and shadow, <name>, but that is not your only role. You have acknowledged that there is merit in knowing the healing arts. This is wise. But before you can know the dark, you must also know the light. And for this, I have a test for you.
North of the cemetery is a wounded Deathguard--Deathguard Kel. He has protected us from gnolls for some time, and needs healing. But, you must also fortify his body before he can return to duty. Do both with your spells, and then return to me.