Not sure I really understood the combat mechanic, but I did win. I mostly used the guy that debuffed the hero a bunch of times and then hit him with the HP draining guys. I didn’t use any of the other monsters.
UI was tricky to use and a bit buggy. I often moved the map instead. I also found it was a little awkward because you were always trying to drop monsters right in front of the hero so it didn’t feel like the map had much game play significance. Realistically I with the current game mechanic it would be a better UX to just click the monsters and have the hero encounter them. If you want drag and drop, I think the position should matter somehow. Perhaps the monsters could combo with other nearby monsters.
Neat idea, and a good foundation for further development.