Madame Mist attended the first of the two meetings at the Great Chamber to decide the new Council of Elders. At the second one, she was nominated by The Torment to become one of the Elders, or else he would not allow the new Sanctuary in Roarhaven could not be used. Erskine Ravel, the new Grand Mage, accepted the offer, on the condition that he took Ghastly Bespoke as his second Elder.
In the sixth book, Madame Mist was not seen many times as she committed her duties as an Elder. She met Skulduggery and Valkyrie when they had something to report. The Torment was meant to have her on the Council for some plan, but as he died, the plan was (apparently) over. When Valkyrie was slashed by Melancholia St Clair, Madame Mist brought in Doctor Nye to help her. Ghastly met with her and disapproved of Nye. Mist simply stated that the Grand Mage allowed it. Mist was shown meeting with The Man with Golden Eyes, suggesting that she was a traitor.
Mist was cunning, deceitful and utterly ruthless. Her fellow Elders suspected that she was a traitor but were unable to prove it until it was too late, pointing at her exceptional skills. Also, she seemed to possess nerves of steel as she remained quite unflinched in a violent confrontation with Remnant-possessed Tanith Low. However, she lost her nerve at the very end of her life. However, when crossed, she could become extremely violent and brutal, possessing no particular finesse in her fight with China Sorrows. The rest of the time, she remained perfectly calm and reserved in public, even when faced with certain death.
Cobwebs hung from her clothes. She wears an authentic black robe that conceals almost all of her features. Her face was covered by a veil.
Beneath her veil, Mist's skin was pale, her lips cracked. Spiders seemed to crawl under her skin instead of blood.
Mist was an extremely powerful Child of the Spider. Her more advanced powers were that she was incredibly strong and fast, taking down a Remnant-possessed Tanith Low without effort. She was almost equally matched in a fight with China Sorrows.
Mist's magic allowed her to form small, white spiders that had both a poisonous and paralysing bite. Her body contained small black spiders, which formed her blood and could be vomited up at will. However, the number of these black spiders available seemed to be lower than those produced by The Torment.
She is one of the two Children of the Spider, the other being Syc, to not have been shown to be able to transform into a giant spider. However, she most likely can,given she was a teacher to Portia, who was proven to have the ability to transform halfway.