So Valindra Shadowmantle appears in the Drizzt Do'urden Neverwinter books. She was one of the coven of high level mages that made up the Arcane Brotherhood in the Hosttower of the Arcane in Lukson, north of Waterdeep. She was the mage that summoned the pit fiend that ended up killing Bruenor Battlehammer in the ruins of Gauntlegrym. Later, she was killed (by Drizz't? Or his elven lover at the time? Can't remember her name. Starts with a D.) And she was "saved" when Arhkan Greely(?), the head of the Arcane Brotherhood and a lich, made her into a lich. (This is all pre-Spellplague).
She shows up later as the head of Thay's efforts to find a crashed Netherese floating city in the Neverwinter Forest and in charge of Thay's forces in the area of Neverwinter (and vying for power and influence in the city), and working for Szass Tam, still a lich. So yeah, not someone we want to get into a fight with LOL