u/Alternative-Floor-92

OK so I hope I'm explaining this well. But, I veered off the usual course I think, fought a boss in the Vanishing Vaults, got the Dark Embrace. Eventually hit a brick wall and looked up if I'd missed anything. I did. ALOT of things. So I went back to the Academy and fought a boss there, and got an eraser upgrade. But the lets player I was watching, got the Dark Embrace, from that same boss, that gave me the eraser. Which confused me. I suppose it means boss drops are, sequential, rather than tied to specific bosses?