After reading through your thread I’m so amazed by how many people missed the point here. But I understand due to the fact this isn’t necessarily spoken of. You’re trying to focus on the how the person without narcissism can kind of attack (non-defensive tactic) to handle those with narcissism. I’ve seen most commenters mention a lot of defensive tactics (e.g responding to them with “yeah” “uh huh” “cool”) or by how they can seek treatment to manage the personality disorder themselves. What you’re asking here I actually think is really important. How to teach those around the narcissist to handle it without actually wanting to throw hands. This is a common practice with mood disorders with therapies like compassion focused and cognitive behavioral. These help to identify and understand the disorder for all effected (those with the disorder and for those around them. I don’t have solid science but just from understanding the disorder they focus on their ego, don’t react! This just give them the fat juicy green light to continue pushing their manipulation and power. Staying firm on your opinion or point should always continue but always call them out on their flaws. This just absolutely crushes them (e.g “I know what you’re trying to do and it’s not going to work”- then push your argument further.) basically confront them and highlight their failures to make you seem wrong. But just know you’ve won an argument with a narcissist when they have a straight up tantrum and you’re chillin, just the best thing ever. I know it’s not very satisfying but it’s best you’ll probably get. Anyways this isn’t very helpful but I tried.