Either this quest, or the quest to Destroy the skeleton transformer, is required to advance in the game. It is not possible to complete both quests.
Sandro, the leader of the Necromancers' Guild, does not feel he can spare any resources to join the Alliance your party is trying to form because they are busy fighting the Temple of the Sun. However, he informs you that if they were to recover the Nightshade Brazier, which allows vampires to range during daylight hours, and which the temple captured, the "war would turn in their favor," and he could then join the Alliance. Sandro asks you to recover the Nightshade Brazier as a condition of their joining the Alliance, and tells you to use Dyson Leland to help with the infiltration.
Monsters[]
Dancing light → Wisp → Will 'o wisp
Acolyte of the Sun → Cleric of the Sun → Priest of the Sun
Walkthrough[]
Sandro can be found in the Necromancers' Guild in Shadowspire, in the top of the southeast tower. Dyson Leland can also be found in the Necromancers' Guild in the top of the southwest tower. The Nightshade brazier is located in a chamber beneath the Temple of the Sun in Murmurwoods.
To gain access to this chamber, you must first take the cleric Dyson Leland into your party since he is the only one who can find the secret button (located in the upper balcony area on the far wall from the entrance) that opens the pathway to the secret chamber. Once you have him, go to the Temple of the Sun. Touch the secret button to get the star-shaped structure in the lower chamber to rise from the floor. Go down the ramp (behind a door you must open) and straight ahead into a little alcove in the star-shape, where you will automatically be taken by one-way elevator to some lower rooms that include the chamber with the Brazier. Do not let Dyson Leland die (or remain unconscious for the exit of the temple) - even after he pushes the button - or Sandro will not recognize that your quest has been completed. It is okay to revive him while still in the temple if he dies - just don't let him stay dead when you exit the temple).
The priests will not turn hostile (assuming you haven't attacked them beforehand) until you pick up the Brazier. When you pick it up, its pedestal will - very very slowly - begin sinking into the floor, all the priests will become hostile, and the walls of the room will sink into the floor (faster than the pedestal is sinking) to reveal many more priests.
The exit from the chamber is through the hole in the floor into which the pedestal is sinking. Once you are out, return with the Brazier to Sandro in the Necromancers' Guild. You will see a CGI of the Necromancers re-activating the Brazier, plus also get your reward, and Sandro will join the Alliance.