Unexpectedly, the fallen angel Luza had his sights set on the angels, his former companions. It's true that since they were the only beings who knew of their existence, it would be more difficult to infiltrate, but he had a different perspective.
While it's true that the angels knew about them, the opposite also applied. Luza was an angel until recently, and one who was part of the upper echelons of his society, so he knew a lot.
He knew the history, strengths, weaknesses, and much more about the angels, so while the angels would be wary of them, it was also true that by knowing them so well, he had a good chance of achieving his goal.
Furthermore, the fallen angels were born from the divinity of the body of the deceased god held by the angels. It's true that this being's divinity was pure, as he is not a fallen god, but its level and intensity are nothing to be underestimated.
