I have had my eye on Magnum hops since I brewed my APA. That beer was an experiment in Glacier hops, which made a pleasant, balanced beer. After tasting it, my thoughts turned to finding a good bittering hop to use for another APA trial. After conducting research on Magnum hops, I think I might have found it.
Origin: Originally Germany. From the sources I read, the Magnum hop variety was bred at the Hop Research Center at Hüll in Germany. I think what we American homebrewers will find are US grown Magnum hops, which sometimes get the Yakima Magnum moniker. It is derived from Galena, although there were some opposing views (Hallertau was also mentioned as a parent hop).
Aroma: Most sources had no real comments about this hop variety’s aroma, so I am thinking it has a nice, nobel aroma. Pleasant, not pungent.
Alpha Acid: Between 12 and 14%
Typical Usage: That high alpha acid and lack of a strong aroma makes Magnum a great bittering hop.
Beer Styles: I would say good for Pales and IPAs. Because of its heritage, and clean bittering power, it probably work for German lagers.