It's not that what you know is wrong - it's that the name has different meanings in other worlds. Honestly, I wouldn't worry too much about it - just be ready to explain to the more zealous ones what it is you actually mean when you say black magic.

[Yeah, the friend part is definitely more palatable.] Maybe. There are a few others I'd like to see here, as well; or better, who I'd like to be back home with.