I think the problem is that the minions get defeated by the bullets from the adventurers, so bats are the best at soaking up bullets.
Also, one small idea: Maybe you could make it so that you can not summon minions when doing that would drain all your mana? It was a little frustrating to have only one enemy left, who was barely alive, and then dying to summoning too many minions.
Don’t worry about my finger, it’s fine! 😄