Congratulations on finishing the game and thanks for the feedback :)
The one shot thingy is weird because you cant lose more than 1HP and get a 1sc invunerability after taking damages, I'll look at it tho
If you are wielding a key when the doors spawns, there is a high chance that one will be a chest room, which contain a weapon of the same rarity as the key (you can upgrade keys), and an amount of gold equivalent to the price of that weapon