The art description that was given to artist James Ryman was this:
Color: Blue creature
Location: A corpse-filled ballroom
Action: Show a female mage who holds a mask of your design that covers only the top half of her face. Below the mask, we can see her grinning mouth. She bows slightly as if she is being applauded by an unseen audience. Around her are several newly dead bodies (but keep it bloodless) – these are the victims of a multi-way standoff she orchestrated. She is dressed in an expensive-looking costume of your design (what would a mage wear to a party?).
Focus: The mage
Mood: You will fight if I say so. You will die if I wish.
And here's how the provocateur got from that description to the final art!