Thanks for giving my game a try and suggestions!
Setting HP and ATK is a preferred way of mine instead of .choose from a pool of monsters, I want to be able to adjust on the fly (ex. The player has 20HP you don't want to let the player die the next 2 hits so you adjust from 10 atk to 9 atk makes the player feel challenging but not kill the player), however, I do consider to make a preset system for the minions atk and hp value, however not enough time to implement it.