You need to tame the ghosts a little, otherwise they are too reckless...

Why? Because if you're lucky and there are almost none left, they have weak defenses. You can attack them with Hunters without fear; one out of two shots should hit, but I can't guarantee it. This is what makes the variety of tactics interesting. I'm currently testing the Ballista on ghosts; if it misses, I finish them off with a strong stack, and they are usually defeated without any problems. You shouldn't eliminate or kill the ghosts; they will lose their individuality and originality.