I've played through 3 runs now and I got really invested in the game. It reminds me a lot of Legend of the Keepers which I've spent countless hours playing. I think you are on to something! Here is some general feedback:
The "world map" could have something more to it, like placing obstacles or sending out patrols or something to affect the monsters progression towards the middle. As is I ended up in what felt like impossible situations where I had 3 monsters in the inner circle and no way of stopping all three.  
I like that there are different aspects to the monsters like "Etheral" and so on, I think you can add more things like that. I also saw items like that granted immunity to status effect that I never saw on the monsters, so I guess that's coming. 
I liked that you could combine weapons and get different upgrades from the caravans, but I think that system could be made clearer and generally how the economy works in the game. 
Overall I had a great time with the game, and I hope you keep working on it!