Me attempting to debate someone about a serious subject in real life is basically like being a wizard using Vancian magic: I try to memorize as many relevant arguments for my opinion as I can fit into my head ahead of time, and if the other person manages to counter all of those, I’m out of luck and have to get away so I can memorize some new ones.
I’m not sure if there’s an analogy for “carry a crossbow so you can shoot enemies once you run out of spells” in this case.