This was a LOT of fun! Definitely not finished, though. Your devlogs mentioned the early Final Fantasy influence, but I also picked up on some Darkest Dungeon vibes, especially with the plague wanderer. I love both of those things, so that to me is awesome. I also like the idea that you're essentially picking the traitor and playing as the villain for the final battle. If it's possible, it might be cool to reverse the final battle so you're playing from the enemy side of the field to further emphasize that.
The biggest problem I found with the game as it currently is, is that the system is very exploitable. You can just stack all of your upgrade points onto a single character and use the other 2 as meat-shields until your chosen character becomes unstoppable, and then if the final battle you can just one-shot your remaining buddies like you've been one-shotting everything up to that point. Atash the Dragonslayer was doing over 1000 damage on a normal attack and was completely unstoppable.
I encountered 2 big bugs in the .93 version, I think. After the battle against Gastan, I don't think the bandits ever landed a hit ever again, even against my un-upgraded character. They maybe hit once because I noticed Atash was down 12 hit points one time, but that might have just been after I raised his health. Also, after that point, Atash would go first, then the bandits, then the Blood Champion, and then Atash would skip his turn and only the Blood Champion would attack. I noticed this happened if the Blood Champion killed the bandit she attacked. If she only wounded him, Atash would go immediately after her. If she killed the bandit though, it would skip him and go right back to the bandits. Also, I have to admit it wasn't *that* fun in its current form, on account of it being the same easy fight repeated a bit too much until the final battle. Once there's more enemies and better balance, that'll even out.
There's a lot of potential to this game. The visual style is rocking, the theme has a really nice hook to it with the betrayal element, and the foundation is solid. Maybe you could add more variety by having other events between the fights, like treasures, a shop equivalent, a choice of minor boons, recovery rooms or downtime between the fights to have some character interactions within your party, events with moral choices, something like that. I've seen lots of rogue-like games include those to break up the monotony of constant battles. If it's going to just be an enemy gauntlet, it might be better to keep it shorter both for balance and for the player's attention. Anyways, good game! I look forward to seeing where you go with it.