Don't know if intentional but the tentacles won't come back if you killed it. Meaning, you can deal with the tentacles first so you don't have to juggle between tentacle attacks and bug attacks.
A thing I dislike is that there's not enough magic to kill the boss in a single full magic bar, so you're forced to stick around until the boss spawns a glowing bug for you to kill and refill your magic bar.
This creates an unnecessary waiting game. If the boss is programmed to only spawn glowing bugs once you have insufficient magic to cast an arrow, that's fine, and that doubles as a tutorial on mana recovery. But currently I don't think that's not the case.
To tie the MC's second chance with her breast expansion status is neat tho. If this a mechanic for every boss fights, that means you will have at least two chances against every boss before getting thrown back to the last checkpoint.
Overall I'm liking it. Excited for where game is heading.