Once you have the quest, the marker will show the location of the Sacellum of Boethiah, which is just east of the city of Windhelm (there IS a path that leads directly up to it, just look around carefully and beware of Ice Trolls). Once you get there you will meat the cultists that worship Boethiah. Talk to the priestess, who will tell you about Boethiah (tell her you aren’t scared by her: Boethiah likes those who believe in themselves after all). She will advance the quest by telling you that to get Boethiah to appear, you have to lead a follower to the Pillar of Sacrifice (which is up that flight of stairs) and get them to touch it. This will trap them, and after they’re trapped you will need to slay them. Looks like we need to find a follower that we don’t mind… killing. You can check our section on companions if you need to find someone.
So after getting a follower that you wouldn’t mind losing, fast travel back to the Sacellum of Boethiah. Head up the stairs to the pillar of sacrifice, then TALK to your follower and tell them you need them to do something. Now, with the new “directing” cursor you’ll get, tell them to activate the pillar. As they do so, strange magic will grab them and hold them to the pillar. Now just take the sacrificial knife and cut them down.
Once you’ve done your horrible deed (and who are we kidding, YOU , sir or madam, are a MONSTER) Boethiah will appear to you, using their corpse. It’s best to use cocky answers when talking to her (“I’m not afraid of you”.) and after some time Boethiah will lead you and all the cultists down the steps (stay at the top if you are best at ranged combat), announcing that she will give a special job to whoever’s left standing…
This initiates a free-for-all amidst all the cultists and your goal is obviously to be the last one standing. If you’re a ranged user (magic/archer) you should be at the top of the steps and can hurt the group from up here. Alternately, you could always let them duke it out until their numbers thin. Just make sure you’re the last one alive. Once everyone is dead, Boethiah will posses another corpse and tell you that your next job is to slay her current champion (whom she’s grown tired of). If you take a look at the map, he’s located at Knifepoint Ridge (west of Falkreath), but there’s a catch: she wants you to do it as STEALTHILY AS POSSIBLE.
Travel to Knifepoint Ridge, which is more or less a bandit encampment. It’s pretty hard to sneak in here due to the watchtowers (try coming in from the east) but the best way to kill and be stealthy here is archery sneak attacks. Go at night so you only have to deal with the watchtowers and one or two bandits around a campfire and proceed to sneak attack everyone to death (don’t worry too much if you get caught or detected: you don’t HAVE to kill everyone stealthily, just do your best). Note that out by the archery range here is a ARCHERY SKILLBOOK called “Vernaccus and Bourlor” that you can pick up. Once you’ve killed everyone out here, enter the mines.
In the mines you’ll be on a much more linear path, so be ready to pick off bandits whenever you see them. Many bandits will be preoccupied either mining or something else to notice you. You have to kill everyone in here, but the champion is in the very back inside of a house structure. If you’re going to sneak attack anyone, make it him as he’s wearing a set of ebony armor. Once you’ve killed everyone, be sure to loot his ebony armor, and then equip it since that’s your new objective. Once you do, Boethiah will speak to you again and name you her champion, giving you the armor as a gift. She’ll also tell you to carry on and do whatever you want as she’s busy “pulling strings”. This ends this quest.