Fantasitc! Had a lot of fun playing through this one. The combat feels really well implemented for a jam game, and the poison mechanic put a really cool spin on dungeon crawling, and really adds to the intensity! The ending is really nice and feels super satisfying too. Amazing job on the sound design also, and I think you mentioned the spritework was used from elsewhere, but it's still really well implemented and the dungeon is laid out nicely and in a very aesthetically pleasing way.
Feedback for improvement: This was already discussed on stream, but the difficulty is far to unforgiving. But it's so very close to ideal in case you want to take this game further! I'd recommend making the health deplete slower still, so the potions are a little more tactical (currently they serve more like short invulnerability timers to run through enemies, as getting hit doesn't matter, your health is gone within seconds anyway).
Another thing would be to have enemies signal in some way before attacking. Particularly the guys that shoot spikes, there is no warning at all (that I could see), so no chance to anticipate/dodge.
I also took damage in a transition coming back down from the north-most key. Luckily my potion hadn't worn off yet, but that would have felt like a cheap death, so maybe tweak the bat positions away from the edge slightly and bear that in mind for any future additions :)
Seriously good job though! Another amazing game, and especially impressive given it's a solo effort.