As her 3 guards has been defeated in the floor below, you climb up the steps, but before you enter the top floor you buy some upgrades with your cells and heal up after that battle from the 3

She stands on top of the massive broken light house, green flames surround the bottom part and the sides of the massive tower... she stands there holding her rapier

Queen: ... She stands there at the middle and stares at the prison, as the fire around burns at that edges of the tower