Thanks for the detailed comment Numbers! It's the kind of comment that would make me go back to my code editor and continue developing Dungeon Mercenary ^^
Doors... yeah doors are tricky, to mitigate the issue you can burn doors down using (if I recall correctly) all fire-based spells (dragon breath, firebolt). Regardings rats, they don't have super powers, it's weird you witness a difference between rats and other monsters.
Regarding the loot, the game is intentionally giving a bit more loot in the beginning, to be "more" noob-friendly. Later on the game makes sure you'll get sufficient loot (if the random generation is too scarce for a few levels, it'll get corrected deep down the dungeon).
Regarding the Force runic, what you're expecting is correct. The more powerful the Force runic, the longer the distance you can push things with, and damage is correlated with the distance; so you should observe that a more powerful Force runic should do more damage. If not there's a bug.
Regarding teleport, thanks for the report; I've never heard this bug before.
Regarding spells being a bit too powerful, that's true. It's really difficult to balance correctly a game like Dungeon Mercenary. Given that I did not do that many iterations, I'm quite happy with the balance. You can think of the spells builds being the "easy" mode while closed-combat builds being more difficult.
Once again, thank you very for your thorough analysis! That's comments like yours that keep small indie devs like me going.