markrosewater answered:

Let me use this question to say something I’ve been wanting to say.

Every time you are unkind to another Magic player, be it in a game, online or through whatever interaction, regardless of your reason, you are hurting the game, you are hurting the community, you are hurting the store you play in, you are hurting the place you gather - most of all, you are hurting other people.

One of the reasons I love the Magic community is because of the kindness they show one another. Don’t be the person that makes Magic something ugly for someone. You love how the Magic community has opened up for you and made you feel welcome. Well, pass that along.

Just imagine that every interaction you have with someone new is the interaction you would have wanted when you were new. A lot of people are attracted to gaming because it is somewhere they feel welcome when there are many other places they do not. Please, please, please do not take that away from people.

Be an ambassador of the game.

Be someone who makes others’ lives better rather than worse.

Be the better person.