Dark Brotherhood - Purifying the Cheydinhal Sanctuary
The most important one is killing Gogron. Gogron gro-Bolmog is one of the toughest fighters, so let’s take the easy way out. He’s also fairly easy to reverse pickpocket. He’ll sit down for a meal at the table later and drop dead.
Ocheeva, Teinaava and Antoinetta Marie can all be killed like this. Teinaava and Antonietta will eat at the table in the Living Quarters. Ocheeva eats in her private room (make sure that nothing is sitting on her plate.
These four are the easy ones. The rest are a little tricky since they don’t officially eat (I watched M’raaj-dar “eat" for awhile but he didn’t pick anything off of the table or have food in his inventory). Vincinte is a vampire. Telanendril wanders for too long and her scripting might get buggy.
Start with Vincinte, ideally on a day when Telanedril isn’t there. That will limit things a bit. Vampires in Oblivion aren’t vulnerable to garlic, but if you read the note in Vincinte’s desk you’ll find that he is very allergic to garlic personally. Antoinetta has been cooking with it a lot and has some in her personal chest by her bed (if you haven’t found some garlic already in random barrels).
If you reverse pickpocket garlic onto Vincinte, he will lose most of the benefits from being a vampire. That makes the fight a bit easier. You can just walk up to him while he’s asleep and start with a sneak attack. He’s a vampire, and therefore very vulnerable to fire. The basic flare spell took off massive chunks of health, so use that while you attack. He should die quickly.
M’raaj-dar is a tough one. The only real and fairly intuitive way to kill him is to ambush him. You can use a sneak attack while he rests or you can attack him while he’s training. He’ll be low on magicka during this time and therefore be less able to use magic against you. Note that his frost spells are really powerful, but he can also knock you down with a power hit. Be ready for a frustrating fight. If you’ve got good armor and he’s low on magicka, then he won’t pack much of a punch. Just grind him down and kill him.
Telaendril is on a special mission for Ocheeva. She goes to different areas and scouts for the Dark Brotherhood. At least for me, she refused to talk outside of the sanctuary. I personally suggest that you just wait inside the sanctuary until one of the days that she comes back. She’s an archer, so the tight spaces aren’t good for her. Just attack and back her into a corner while you slice away.
Once she dies, you’re finished with the quest. Make sure that you loot all the bodies for their unique gear and keys, then use those keys to also loot the personal chests by their bedsides.
When you’re ready, go back to Lucien Lachance and report your success. He’ll tell you about the new dead drop system. You need to walk out to the marked spot on Hero Hill to get your next mission.