Ravanna

Ravanna, the Queen of Diamonds is a member of the Black Deck. She is an enchantress who specializes in written magics; once the victim reads the magical writing, they fall under her control. Elven Secrets first became aware of her when it became apparent that she had ensorcelled the domestic servants of House Falladren into stealing the House's valuable enchanting table. When they finally met, she used her power to make Vesryn attempt to cut his own throat. They met again in the tower near Whiteholme. Although Elven Secrets could easily have killed her, she claimed that if they did, her mole within Regulus Investigations would kill Dahlia. They thus allowed her to teleport away. According to Clement Percy, his assistant Mr. Redding indeed proved to be under the Queen of Diamonds' control.