I encountered 3 slight bugs:

First, with the black hole spell, the juice the monsters leave sometimes stay stagnet in the air, this usually happens if you fly far away from the monsters while the black hole spell is doing it's thing. Secondly, a bug that whenever you get a large jukebox, go to hogan's to shrink it, and then use the "copy weapon" spell, the jukeboxes copied seem to remain the size before hogan's alteration and launches you in the direction the jukebox is being held (if you are a speedrunner reading this, I guess you can use this bug to fly fast without needing flight). Thirdly, you can still eat the monster even if you use a black hole spell, the black hole does not like that and smushes against your face, though this isn't a big problem because I haven't gotten some physic breaking thing from this like the jukebox bug. 

The slight idea:

Maybe have the black hole spells (and other spells?) take juice away from the kill? At least with the black hole spell because it's weird to see the juice come to you instead of going to the dark matter. I feel like the spells using (maybe just some of) the juice it finds would be good for 2 reasons: 1, to make it where you still want to swing swords because you don't get as much juice out of using magic, so magic would act more of a room cleaner than a "get juice fast" scheme. 2, because it really slows down your computer with all of the effects from a big ball of anti-matter gets compounded by the game having the juice try to go to you.

Nerfing the black-hole spell (and other spells?) with getting less juice back might be rude to the mage players though, so take it with a grain of salt (but not the bugs, the bugs are there)