Necromancer Altar
From the OblivioWiki – your guide to everything Oblivion
A Necromancer Altar is required to convert a Grand Soul Gem into a Black Soul Gem. They can only be used once a week on a certain night of the week. On the night one can be used, it will be illuminated by a purple beam of light shooting downward from the sky (see screenshot). This beam of light is more noticible further away from the altar; if you are standing directly in front of the altar, it is easy to miss. However, if there is a Necromancer present, then it is the right day (correct days end at midnight).
The grand soul gem must be empty. You can hit the altar with a touch or ranged based soul trap spell, for lower class character or non magic user, touch is more accessible as it requires a lot less magicka and cheaper to purchase as well as does not require high mysticism skill level.
The altar is active from midnight to midnight on the active day.
[edit] Using a Necromancer Altar
To use a Necromancer Altar, put the empty Grand Soul Gems you want to convert into the altar on a night when the altar is active. Close the altar and cast a Soul Trap spell on the altar to convert one of the Grand Soul Gems into a Black Soul Gem. This process is repeatable - cast Soul Trap as many times as you have Grand Soul Gems to convert. (See screenshots for the before and after)
 Necromancer Altar outside Dark Fissure |
 Active altar with the purple beam of light on it |
 Place an empty Grand Soul Gem into the altar |
 After casting Soul Trap on the altar you will find a Black Soul Gem inside |
[edit] Necromancer Altar Locations
Each altar is only active on a particular day of the week. The specific days vary from game to game (or on some games it may be completely random).
Azura's Star does not succesfully turn into a black soul gem.
