Thestra, Wife of the Storm

The Wife of the Storm, Thestra is the Storm Giant Queen of Cloud City. Possessing the ability to "Sense Motive" which consists of hitting her target with a bolt of electricity.
However during the course of the Cloud City Arc, it was revealed that Thestra was either under the influence of fiends or was actively commanding them herself when she killed her king in cold blood. Terrell Temptus, The Storm King's body was left on the floor of the Throne Room. Later the Elder Oblex vacuumed the King's Essence, the Doldrumns, off the floor and used it to kick off a cascade of events that started with framing a charmed adventurer named Fen Darkeyes for the King's Murder and ended with Thestra taking the Storm Throne for herself.