The Ghost Flame
Boss: Purple Named - Powerful Boss
Attack: Spellcasting, 4-second Silenced effect
Special Qualities: Healed by Negative, Teleport
Description: The Ghost Flame begins the battle covered in a shadowy ward that blocks all damage. When one of her apprentices falls, she loses this shield. However, she cannot be killed until Death's Teeth is slain, healing to 40% health whenever she reaches 15%.
The Ghost Flame mostly uses negative spells. Pale Masters using negative healing near her will find themselves the target of a 20-second effect which makes them vulnerable to Negative damage, although their own spells will not affect them.
The Ghost Flame does not actually die at the end of Skeletons in the Closet, instead being sent to a pocket dimension by Vecna; consequently, she has no Monster Manual entry. The Archlich's dialogue implies she will be back for a rematch at some time in the future.
A number of scrolls telling the story of The Ghost Flame and Death's Teeth can be found in Isle of Dread (wilderness). Additionally, notes from the journal of the dead Doctor Lifestone suggest her real name is Yarrow.