This game is excellent, but I do have several comments on the current state of the game mostly relating to the structuring of instant-death moves that several enemies can use.
To remedy this, I would recommend two potential solutions:
a) Simplest: Tell the player indirectly that they are fucked (to hint that there is no trick to replaying the fight) right before they are executed. This breaks the combat flow and immediately communicates to the player that this fight was not winnable. I would also make them
way stronger initially so this doesn't come as some sort of unpleasant surprise (maybe nearly full killing each of your characters per-attack right at the beginning.
b) Make the fight unwinnable, but scale the power more smoothly (either start higher, or grow slower indicating that the enemy is playing with you). Particularly for 2) above, I think slow power scaling would be the way to go (even if the outcome is locked to one result), as the player could still have a sense of accomplishment for how long they survived.
This also leads into one other suggestion I would make on equipment: The immortality grimoire. This is a
really cool idea strategically, but it has one major flaw: it still kills you if you don't immediately heal every turn. I think it would be better if this was a more direct analog of endure from the pokemon games, where it leaves you with 1 hp instead of 0. If your concern is people casting it endlessly, then simply make the cooldown 4 turns rather than 3 so that they have to survive at least one round without dying to cast it again. Or, if your goal was to lock up the players moves to force them to only do one thing while losing it (which I doubt), you could simply make it last 1 turn so they have to constantly re-cast it to survive. As it stands, you can cast it and still die immediately if you don't use all of your moves to heal. That doesn't sound very immortal to me
All in all a fantastic game thus far! I look forward to where you take it!