Looks like you understood the game very well :-) Kudos to you.
Indeed health is the most valuable resource, that is why the health spell is vital.
I think your run is typical of how one should win the game (another kinda easy way to do is to use a vampirism weapon) and that why I think I should make waiting less powerful, and also going back to earlier depths should be made impossible or difficult; otherwise it's too easy to grasp early rewards while being in the last depths. To make waiting less powerful, I could spawn monsters when you wait too much; or I could tie spell rejuvenation to monster-killing instead of time-passing. Or I could turn spells into consumables, once you've used a spell once or more; it disappears. Or I could make the depths not connected, i.e. like different missions instead of a full dungeon. What do you think ?
Regarding paralysis, could it be possible that you were slowed down while it seems paralysis wasn't lasting enough ? If you're paralysed, you do not witness some of the monsters' turns.
Regarding protection, I don't think there's a bug; but because protection stacks; every-time you cast it, your total health increases which means the next casting will make the orange bar grow a bit less.
On a final note, I'm glad you used quite a few different items and spells to do your winning run. This shows that many items have a distinct purpose :-)