You searched for nightveil
Helpfile keywords: nightveil
Syntax: cast nightveil (<object>) Casting nightveil on an object which is glowing will snuff out the light surrounding the object, removing the glow flag. If an item doesn't have the glow flag, it will give it the dark flag. Casting nightveil on a room will cause it to become shrouded in darkness. Players or mobiles entering the room will not be able to see the surroundings without the darkvision spell if there are no lights in the room. Some areas (such as recall) do not allow this spell to be cast in its rooms.
Related helpfiles: Darkvision, Illumination.