I want to hear about black magic. I've only heard a little at the academy, but I'm interested.
Literal
Black-magic [genitive-の] story [object-を] hear-want [polite-です]. Academy [at-では] surface-only hear-past-[progressive-ている] [but-が] interest exists.
さわり ('the gist, the essential part, a taste of') is a noun with two seemingly opposite meanings: it can mean 'touch, contact' or specifically in music, 'the highlight, the essence' — here used to mean 'just a little bit.' しか~ない ('only') restricts it further. 学院 ('academy, institute') suggests a fantasy or specialized-school setting.