You get points from the Shadow Worshippers depending on the quality of the sacrifices (monks from the Temple of Light get most) and if they take place at night. To convince people to be sacrificed isn't easy, so you need to get them to follow you to the mystery location instead. After you accumulate 2000 points you get a special prize. To do this, head to the Temple of Light and impress the monks there suitably to get them to follow you (you should be able to get four at once at least) and then head to the Temple of Shadows (fast travel works for followers too). Lead them onto the bloody platform in front of the sacrificial wheel and let it do its work to get a healthy batch of points. Repeat this process until you hit 2000. Remember, more points are given if the sacrifice s made at night. You should suffer around 50 evil points and 30 corruption points for each successful sacrifice.
After this you can get a legendary weapon by making a particularly gruesome sacrifice in the hour after midnight. Use fast travel to get there at the right time and if your sacrifice was gruesome enough (try as many monks as possible, even your husband or wife to really show your dedication!).
