I like the game, but have some issues with the balance of the game.
Packs of warriors that spawn literally mows down everything. I think that the way the game's designed, warriors are overpowered no matter how slow they are because of how they can gather together and mow down everything you summon because they are so tanky that they stay on the field, deals insane damage, spawns quite frequently, and because of how resilient they are, warriors from behind will eventually catch up and continue building a literal warrior "wall" towards you that's basically impossible to break. Even with their lower attack speed, since they seem to love coming in packs, this disadvantage is immediately mitigated by the sheer number of warriors that march, allowing of them to lay strikes one at a time, killing literally everything. No matter what I summon (army of skeletons, zombies, vamps), they seem to mow down everything no matter what.
Your summons also spend too much time doing nothing but standing around while nearby summons fight despite being extremely close. This allows for packs of enemies (especially warriors) to pick out your summons one by one very easily. Perhaps make them a bit more aggressive? Also the fact that warriors can literally one-shot the most expensive unit doesn't feel very fair. I know vampires can drain HP and thus a bit harder to balance, but with all their cost and the frequency of warriors that somehow appear in packs, it's bit ridiculous how all of them die off the very moment a pack of warriors (which spawns very frequently) come along in my opinion. The other units don't fair much better either against warrior packs, but at least they can somewhat last a bit before being inevitably trampled by warrior walls.
Apart from these, this game's pretty good and the idea is pretty neat. Balancing needs quite a lot of work, but apart from that, good job.