It appears to be a ranged attacker, Anne detailing how she was irradiated by the radioactive fallout from Lucifer's particle beams, after her DC Coat was blasted off by it.
- Anne: "It's probably from when I fought Lucifer a few years ago."
- Dry: "It's been three years since a Type Zero of B-Class or higher..."
The large scale battle in which Lucifer and Anne fought in resulted with her as the only survivor from the human forces, but from Leo's commentary, it appears that even then, Lucifer was on the brink of defeat, managing to escaping before Anne could finish him.
He reappears later in Knight Fall Ch 2 and gets killed in the battle with Lea Zail and her Knights.