A simple probably
Why you belive low HP mean easy to kill?When you have not AOE baby, only need two or three enemies can block you attack, protect plums face you first baby, and you lost
"'ve just never encountered this problem" is not mean this problem is not existent, and i am not sure what you mean " block the enemies that block your shots", you mean kill that? Or use some baby like "Cube of Meat"? Whatever which is you choose, they all lead to you place more baby in a line and plums will easy to fly