Hello, thanks a lot for taking the time to play my game! I really appreciate your feedback, and you're absolutely right about the skulls in the mage fight. I had planned to fix that since I noticed it during playtesting, but I forgot to do it in the end, my bad! T_T
As for the bosses, they were actually scaled up using Aseprite's scale tool. Technically, the pixels are the same size, but since the original boss sprites were so small and because of the artstyle, it's hard to notice that they are properly scaled in game. I uploaded a screenshot from Aseprite so you can check it out.
And thank you again for taking the time to write this comment! :)
Edit: I really loved the mechanics of your game really satisfying and fun! Probably the game I enjoyed the most in this jam. :)