Succubus is one of the first real notable boss battles in Castlevania: Symphony of the Night. After all, a succubus is one of the most unforgettable creatures of darkness.
She apparently attacks Alucard in a dream world, whatever that means. First mocking him by showing him a vision of his human mother Lisa being executed by people.
Eventually you get to fight her and she flies in the air mostly. Not super easy to dodge the attacks, but I don’t remember her being necessarily difficult to defeat.
When Alucard kills her, he mentioned something about her soul wandering in the world differently because they were in the dream world. Tough luck.