isnt the babadook powered by emotions already? like grief, stress, and mourning without the ability to let go? which letting go and dealing with your grief was supposed to "defeat" the babadook, or something like that?
Powered by emotions that are strong for you, not necessarily grief and depression.
And you can't defeat it, just overcome it, which some people are incapable of such things.
If you were to be one scary legend I think you might be kenjõrõ. A japanese legend about a seductive ghost appearing in red light districts that preys on men and kills them when they get seduced by her.